/*******************************************************************************
 * Copyright (c) 2000, 2008 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *     
 * Port to the D programming language:
 *     Jacob Carlborg <doob@me.com>
 *******************************************************************************/
module dwt.accessibility.Accessible;

import dwt.dwthelper.utils;

import dwt.DWT;
import dwt.DWTException;
import dwt.graphics.Point;
import dwt.graphics.Rectangle;
import dwt.internal.cocoa.NSArray;
import dwt.internal.cocoa.NSMutableArray;
import dwt.internal.cocoa.NSNumber;
import dwt.internal.cocoa.NSObject;
import dwt.internal.cocoa.NSPoint;
import dwt.internal.cocoa.NSRange;
import dwt.internal.cocoa.NSSize;
import dwt.internal.cocoa.NSString;
import dwt.internal.cocoa.NSValue;
import dwt.internal.cocoa.OS;
import cocoa = dwt.internal.cocoa.id;
import dwt.widgets.Composite;
import dwt.widgets.Control;
import dwt.widgets.Display;
import dwt.widgets.Monitor;
import dwt.widgets.Shell;

import tango.core.Thread;
import tango.util.container.HashMap;

import dwt.accessibility.ACC;
import dwt.accessibility.AccessibleControlEvent;
import dwt.accessibility.AccessibleEvent;
import dwt.accessibility.AccessibleListener;
import dwt.accessibility.AccessibleControlListener;
import dwt.accessibility.AccessibleTextEvent;
import dwt.accessibility.AccessibleTextListener;
import dwt.accessibility.SWTAccessibleDelegate;
import dwt.dwthelper.associativearray;

/**
 * Instances of this class provide a bridge between application
 * code and assistive technology clients. Many platforms provide
 * default accessible behavior for most widgets, and this class
 * allows that default behavior to be overridden. Applications
 * can get the default Accessible object for a control by sending
 * it <code>getAccessible</code>, and then add an accessible listener
 * to override simple items like the name and help string, or they
 * can add an accessible control listener to override complex items.
 * As a rule of thumb, an application would only want to use the
 * accessible control listener to implement accessibility for a
 * custom control.
 * 
 * @see Control#getAccessible
 * @see AccessibleListener
 * @see AccessibleEvent
 * @see AccessibleControlListener
 * @see AccessibleControlEvent
 * @see <a href="http://www.eclipse.org/swt/snippets/#accessibility">Accessibility snippets</a>
 * @see <a href="http://www.eclipse.org/swt/">Sample code and further information</a>
 * 
 * @since 2.0
 */
public class Accessible {
    
    static NSString[] baseAttributes;
    
    static NSString[] baseTextAttributes;
    
    static NSString[] baseParameterizedAttributes;
    
    
    NSMutableArray attributeNames = null;
    NSMutableArray parameterizedAttributeNames = null;
    NSMutableArray actionNames = null;
    
    AccessibleListener[] accessibleListeners;
    AccessibleControlListener[] accessibleControlListeners;
    AccessibleTextListener[] accessibleTextListeners;
    Control control;
    
    SWTAccessibleDelegate[int] children;
    
    this (Control control) {
        
        this.control = control;
        
        baseAttributes = [ 
                          OS.NSAccessibilityRoleAttribute,
                          OS.NSAccessibilityRoleDescriptionAttribute,
                          OS.NSAccessibilityHelpAttribute,
                          OS.NSAccessibilityFocusedAttribute,
                          OS.NSAccessibilityParentAttribute,
                          OS.NSAccessibilityChildrenAttribute,
                          OS.NSAccessibilityPositionAttribute,
                          OS.NSAccessibilitySizeAttribute,
                          OS.NSAccessibilityWindowAttribute,
                          OS.NSAccessibilityTopLevelUIElementAttribute
                          ];
        
        baseTextAttributes = [
                              OS.NSAccessibilityNumberOfCharactersAttribute,
                              OS.NSAccessibilitySelectedTextAttribute,
                              OS.NSAccessibilitySelectedTextRangeAttribute,
                              OS.NSAccessibilityInsertionPointLineNumberAttribute,
                              OS.NSAccessibilitySelectedTextRangesAttribute,
                              OS.NSAccessibilityVisibleCharacterRangeAttribute,
                              OS.NSAccessibilityValueAttribute
                              ];
        
        baseParameterizedAttributes = [
                                       OS.NSAccessibilityStringForRangeParameterizedAttribute,
                                       OS.NSAccessibilityRangeForLineParameterizedAttribute
                                       ];
    }
    
    /**
	 * Invokes platform specific functionality to allocate a new accessible object.
	 * <p>
	 * <b>IMPORTANT:</b> This method is <em>not</em> part of the public
	 * API for <code>Accessible</code>. It is marked public only so that it
	 * can be shared within the packages provided by SWT. It is not
	 * available on all platforms, and should never be called from
	 * application code.
	 * </p>
	 *
	 * @param control the control to get the accessible object for
	 * @return the platform specific accessible object
	 */
	public static Accessible internal_new_Accessible(Control control) {
		return new Accessible(control);
	}
    
    /**
     * Adds the listener to the collection of listeners who will
     * be notified when an accessible client asks for certain strings,
     * such as name, description, help, or keyboard shortcut. The
     * listener is notified by sending it one of the messages defined
     * in the <code>AccessibleListener</code> interface.
     *
     * @param listener the listener that should be notified when the receiver
     * is asked for a name, description, help, or keyboard shortcut string
     *
     * @exception IllegalArgumentException <ul>
     *    <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
     * </ul>
     * @exception DWTException <ul>
     *    <li>ERROR_WIDGET_DISPOSED - if the receiver's control has been disposed</li>
     *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver's control</li>
     * </ul>
     *
     * @see AccessibleListener
     * @see #removeAccessibleListener
     */
    public void addAccessibleListener (AccessibleListener listener) {
        checkWidget();
        if (listener is null) DWT.error(DWT.ERROR_NULL_ARGUMENT);
        accessibleListeners.addElement(listener);
    }
    
    /**
     * Adds the listener to the collection of listeners who will
     * be notified when an accessible client asks for custom control
     * specific information. The listener is notified by sending it
     * one of the messages defined in the <code>AccessibleControlListener</code>
     * interface.
     *
     * @param listener the listener that should be notified when the receiver
     * is asked for custom control specific information
     *
     * @exception IllegalArgumentException <ul>
     *    <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
     * </ul>
     * @exception DWTException <ul>
     *    <li>ERROR_WIDGET_DISPOSED - if the receiver's control has been disposed</li>
     *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver's control</li>
     * </ul>
     *
     * @see AccessibleControlListener
     * @see #removeAccessibleControlListener
     */
    public void addAccessibleControlListener(AccessibleControlListener listener) {
        checkWidget();
        if (listener is null) DWT.error(DWT.ERROR_NULL_ARGUMENT);
        accessibleControlListeners.addElement(listener);
    }
    
    /**
     * Adds the listener to the collection of listeners who will
     * be notified when an accessible client asks for custom text control
     * specific information. The listener is notified by sending it
     * one of the messages defined in the <code>AccessibleTextListener</code>
     * interface.
     *
     * @param listener the listener that should be notified when the receiver
     * is asked for custom text control specific information
     *
     * @exception IllegalArgumentException <ul>
     *    <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
     * </ul>
     * @exception DWTException <ul>
     *    <li>ERROR_WIDGET_DISPOSED - if the receiver's control has been disposed</li>
     *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver's control</li>
     * </ul>
     *
     * @see AccessibleTextListener
     * @see #removeAccessibleTextListener
     * 
     * @since 3.0
     */
    public void addAccessibleTextListener (AccessibleTextListener listener) {
        checkWidget ();
        if (listener is null) DWT.error (DWT.ERROR_NULL_ARGUMENT);
        accessibleTextListeners.addElement (listener);      
    }
    
    public cocoa.id internal_accessibilityActionDescription(NSString action, int childID) {
        // TODO No action support for now.
        return NSString.stringWith("");
    }
    
    public NSArray internal_accessibilityActionNames(int childID) {
        // The supported action list depends on the role played by the control.
        AccessibleControlEvent event = new AccessibleControlEvent(this);
        event.childID = childID;
        event.detail = -1;
        for (int i = 0; i < accessibleControlListeners.size(); i++) {
            AccessibleControlListener listener = elementAt(accessibleControlListeners, i);
            listener.getRole(event);
        }
        
        // No accessible listener is overriding the role of the control, so let Cocoa return the default set for the control.
        if (event.detail is -1) {
            return null;
        }
        
        if ((childID is ACC.CHILDID_SELF) && (actionNames !is null)) {
            return retainedAutoreleased(actionNames);
        }
        
        NSMutableArray returnValue = NSMutableArray.arrayWithCapacity(5);
        
        switch (event.detail) {
            case ACC.ROLE_PUSHBUTTON:
            case ACC.ROLE_RADIOBUTTON:
            case ACC.ROLE_CHECKBUTTON:
            case ACC.ROLE_TABITEM:
                returnValue.addObject(OS.NSAccessibilityPressAction);
                break;
        }
        
        switch (event.detail) {
            case ACC.ROLE_COMBOBOX:
                returnValue.addObject(OS.NSAccessibilityConfirmAction);
                break;
        }
        
        
        if (childID is ACC.CHILDID_SELF) {
            actionNames = returnValue;
            actionNames.retain();
            return retainedAutoreleased(actionNames);
        } else {
            // Caller must retain if they want to hold on to it.
            return returnValue;
        }
    }
    
    public NSArray internal_accessibilityAttributeNames(int childID) {
        // The supported attribute set depends on the role played by the control.
        // We may need to add or remove from the base set as needed.
        AccessibleControlEvent event = new AccessibleControlEvent(this);
        event.childID = childID;
        event.detail = -1;
        for (int i = 0; i < accessibleControlListeners.size(); i++) {
            AccessibleControlListener listener = accessibleControlListeners.elementAt(i);
            listener.getRole(event);
        }
        
        // No accessible listener is overriding the role of the control, so let Cocoa
        // return the default set for the control.
        if (event.detail is -1)
            return null;
        
        if ((childID is ACC.CHILDID_SELF) && (attributeNames !is null)) {
            return retainedAutoreleased(attributeNames);
        }
        
        NSMutableArray returnValue = NSMutableArray.arrayWithCapacity(baseAttributes.length);
        
        /* Add our list of supported attributes to the array.
         * Make sure each attribute name is not already in the array before appending.
         */
        for (int i = 0; i < baseAttributes.length; i++) {
            if (!returnValue.containsObject(baseAttributes[i])) {
                returnValue.addObject(baseAttributes[i]);
            }
        }
        
        if (accessibleTextListeners.size() > 0) {
            for (int i = 0; i < baseTextAttributes.length; i++) {
                if (!returnValue.containsObject(baseTextAttributes[i])) {
                    returnValue.addObject(baseTextAttributes[i]);
                }
            }
        }
        
        // The following are expected to have a value (AXValue)
        switch (event.detail) {
            case ACC.ROLE_CHECKBUTTON:
            case ACC.ROLE_RADIOBUTTON:
            case ACC.ROLE_LABEL:
            case ACC.ROLE_TABITEM:
            case ACC.ROLE_TABFOLDER:
                returnValue.addObject(OS.NSAccessibilityValueAttribute);
                break;
        }
        
        // The following are expected to report their enabled status (AXEnabled)
        switch (event.detail) {
            case ACC.ROLE_CHECKBUTTON:
            case ACC.ROLE_RADIOBUTTON:
            case ACC.ROLE_LABEL:
            case ACC.ROLE_TABITEM:
            case ACC.ROLE_PUSHBUTTON:
            case ACC.ROLE_COMBOBOX:
                returnValue.addObject(OS.NSAccessibilityEnabledAttribute);
                break;
        }
        
        // The following are expected to report a title (AXTitle)
        switch (event.detail) {
            case ACC.ROLE_CHECKBUTTON:
            case ACC.ROLE_RADIOBUTTON:
            case ACC.ROLE_PUSHBUTTON:
            case ACC.ROLE_TABITEM:
                returnValue.addObject(OS.NSAccessibilityTitleAttribute);
                break;
        }
        
        // Accessibility verifier says these attributes must be reported for combo boxes.
        if (event.detail is ACC.ROLE_COMBOBOX) {
            returnValue.addObject(OS.NSAccessibilityExpandedAttribute);
        }
        
        // Accessibility verifier says these attributes must be reported for tab folders.
        if (event.detail is ACC.ROLE_TABFOLDER) {
            returnValue.addObject(OS.NSAccessibilityContentsAttribute);
            returnValue.addObject(OS.NSAccessibilityTabsAttribute);
        }
        
        /*
         * Only report back sub-roles when the DWT role maps to a sub-role.
         */
        if (event.detail !is -1) {
            String osRole = roleToOs(event.detail);
            
            if (dwt.dwthelper.utils.indexOf(osRole, ':') is -1)
                returnValue.removeObject(OS.NSAccessibilitySubroleAttribute);
        }
        
        /*
         * Children never return their own children, so remove that attribute.
         */
        if (childID !is ACC.CHILDID_SELF) {
            returnValue.removeObject(OS.NSAccessibilityChildrenAttribute);
        }
        
        if (childID is ACC.CHILDID_SELF) {
            attributeNames = returnValue;
            attributeNames.retain();
            return retainedAutoreleased(attributeNames);
        } else {
            // Caller must retain if necessary.
            return returnValue;
        }
    }
    
    public cocoa.id internal_accessibilityAttributeValue(NSString attribute, int childID) {
        if (attribute.isEqualToString(OS.NSAccessibilityRoleAttribute)) return getRoleAttribute(childID);
        if (attribute.isEqualToString(OS.NSAccessibilitySubroleAttribute)) return getSubroleAttribute(childID);
        if (attribute.isEqualToString(OS.NSAccessibilityRoleDescriptionAttribute)) return getRoleDescriptionAttribute(childID);
        if (attribute.isEqualToString(OS.NSAccessibilityExpandedAttribute)) return getExpandedAttribute(childID);
        if (attribute.isEqualToString(OS.NSAccessibilityHelpAttribute)) return getHelpAttribute(childID);
        if (attribute.isEqualToString(OS.NSAccessibilityTitleAttribute)) return getTitleAttribute(childID);
        if (attribute.isEqualToString(OS.NSAccessibilityValueAttribute)) return getValueAttribute(childID);
        if (attribute.isEqualToString(OS.NSAccessibilityEnabledAttribute)) return getEnabledAttribute(childID);
        if (attribute.isEqualToString(OS.NSAccessibilityFocusedAttribute)) return getFocusedAttribute(childID);
        if (attribute.isEqualToString(OS.NSAccessibilityParentAttribute)) return getParentAttribute(childID);
        if (attribute.isEqualToString(OS.NSAccessibilityChildrenAttribute)) return getChildrenAttribute(childID);
        if (attribute.isEqualToString(OS.NSAccessibilityContentsAttribute)) return getChildrenAttribute(childID);
        // FIXME:  There's no specific API just for tabs, which won't include the buttons (if any.)
        if (attribute.isEqualToString(OS.NSAccessibilityTabsAttribute)) return getTabsAttribute(childID);
        if (attribute.isEqualToString(OS.NSAccessibilityWindowAttribute)) return getWindowAttribute(childID);
        if (attribute.isEqualToString(OS.NSAccessibilityTopLevelUIElementAttribute)) return getTopLevelUIElementAttribute(childID);
        if (attribute.isEqualToString(OS.NSAccessibilityPositionAttribute)) return getPositionAttribute(childID);
        if (attribute.isEqualToString(OS.NSAccessibilitySizeAttribute)) return getSizeAttribute(childID);
        if (attribute.isEqualToString(OS.NSAccessibilityDescriptionAttribute)) return getDescriptionAttribute(childID);
        if (attribute.isEqualToString(OS.NSAccessibilityNumberOfCharactersAttribute)) return getNumberOfCharactersAttribute(childID);
        if (attribute.isEqualToString(OS.NSAccessibilitySelectedTextAttribute)) return getSelectedTextAttribute(childID);
        if (attribute.isEqualToString(OS.NSAccessibilitySelectedTextRangeAttribute)) return getSelectedTextRangeAttribute(childID);
        if (attribute.isEqualToString(OS.NSAccessibilityInsertionPointLineNumberAttribute)) return getInsertionPointLineNumberAttribute(childID);
        if (attribute.isEqualToString(OS.NSAccessibilitySelectedTextRangesAttribute)) return getSelectedTextRangesAttribute(childID);
        if (attribute.isEqualToString(OS.NSAccessibilityVisibleCharacterRangeAttribute)) return getVisibleCharacterRangeAttribute(childID);
        
        // If this object don't know how to get the value it's up to the control itself to return an attribute value.
        return null;
    }
    
    public cocoa.id internal_accessibilityAttributeValue_forParameter(NSString attribute, cocoa.id parameter, int childID) {
        if (attribute.isEqualToString(OS.NSAccessibilityStringForRangeParameterizedAttribute)) return getStringForRangeAttribute(parameter, childID);
        if (attribute.isEqualToString(OS.NSAccessibilityRangeForLineParameterizedAttribute)) return getRangeForLineParameterizedAttribute(parameter, childID);      
        return null;
    }
    
    // Returns the UI Element that has the focus. You can assume that the search for the focus has already been narrowed down to the receiver.
    // Override this method to do a deeper search with a UIElement - e.g. a NSMatrix would determine if one of its cells has the focus.
    public cocoa.id internal_accessibilityFocusedUIElement(int childID) {
        AccessibleControlEvent event = new AccessibleControlEvent(this);
        event.childID = ACC.CHILDID_MULTIPLE; // set to invalid value, to test if the application sets it in getFocus()
        event.accessible = null;
        for (int i = 0; i < accessibleControlListeners.size(); i++) {
            AccessibleControlListener listener = accessibleControlListeners.elementAt(i);
            listener.getFocus(event);
        }
        
        // The listener did not respond, so let Cocoa figure it out.
        if (event.childID is ACC.CHILDID_MULTIPLE)
            return null;
        
        /* The application can optionally answer an accessible. */
        if (event.accessible !is null) {
            return new cocoa.id(OS.NSAccessibilityUnignoredAncestor(event.accessible.control.view.id));
        }
        
        /* Or the application can answer a valid child ID, including CHILDID_SELF and CHILDID_NONE. */
        if (event.childID is ACC.CHILDID_SELF || event.childID is ACC.CHILDID_NONE) {
            return new cocoa.id(OS.NSAccessibilityUnignoredAncestor(control.view.id));
        }   
        
        return new cocoa.id(OS.NSAccessibilityUnignoredAncestor(childIDToOs(event.childID).id));
    }
    
    // Returns the deepest descendant of the UIElement hierarchy that contains the point. 
    // You can assume the point has already been determined to lie within the receiver.
    // Override this method to do deeper hit testing within a UIElement - e.g. a NSMatrix would test its cells. The point is bottom-left relative screen coordinates.
    public cocoa.id internal_accessibilityHitTest(NSPoint point, int childID) {
        AccessibleControlEvent event = new AccessibleControlEvent(this);
        event.x = cast(int) point.x;
        dwt.widgets.Monitor.Monitor primaryMonitor = Display.getCurrent().getPrimaryMonitor();
        event.y = cast(int) (primaryMonitor.getBounds().height - point.y);
        
        // Set an impossible value to determine if anything responded to the event.
        event.childID = ACC.CHILDID_MULTIPLE;
        for (int i = 0; i < accessibleControlListeners.size(); i++) {
            AccessibleControlListener listener = accessibleControlListeners.elementAt(i);
            listener.getChildAtPoint(event);
        }
        
        // The listener did not respond, so let Cocoa figure it out.
        if (event.childID is ACC.CHILDID_MULTIPLE)
            return null;
        
        if (event.accessible !is null) {
            return new cocoa.id(OS.NSAccessibilityUnignoredAncestor(event.accessible.control.view.id));
        }
        
        if (event.childID is ACC.CHILDID_SELF || event.childID is ACC.CHILDID_NONE) {
            return new cocoa.id(OS.NSAccessibilityUnignoredAncestor(control.view.id));
        }
        
        return new cocoa.id(OS.NSAccessibilityUnignoredAncestor(childIDToOs(event.childID).id));
    }
    
    public bool internal_accessibilityIsAttributeSettable(NSString attribute, int childID) {
        return false;
    }
    
    // Return YES if the UIElement doesn't show up to the outside world - i.e. its parent should return the UIElement's children as its own - cutting the UIElement out. E.g. NSControls are ignored when they are single-celled.
    public bool internal_accessibilityIsIgnored(int childID) {
        return false;
    }
    
    // parameterized attribute methods
    public NSArray internal_accessibilityParameterizedAttributeNames(int childID) {
        
        if ((childID is ACC.CHILDID_SELF) && (parameterizedAttributeNames !is null)) {
            return retainedAutoreleased(parameterizedAttributeNames);
        }
        
        NSMutableArray returnValue = NSMutableArray.arrayWithCapacity(4);
        
        if (accessibleTextListeners.size() > 0) {
            for (int i = 0; i < baseParameterizedAttributes.length; i++) {
                if (!returnValue.containsObject(baseParameterizedAttributes[i])) {
                    returnValue.addObject(baseParameterizedAttributes[i]);
                }
            }
            
        }
        
        if (childID is ACC.CHILDID_SELF) {
            parameterizedAttributeNames = returnValue;
            parameterizedAttributeNames.retain();
            return retainedAutoreleased(parameterizedAttributeNames);
        } else {
            // Caller must retain if they want to keep it.
            return returnValue;
        }
    }
    
    public void internal_accessibilityPerformAction(NSString action, int childID) {
        // TODO Auto-generated method stub
        // No action support for now.
    }
    
    /**
     * Returns the control for this Accessible object. 
     *
     * @return the receiver's control
     * @since 3.0
     */
    public Control getControl() {
        return control;
    }
    
    /**
     * Invokes platform specific functionality to dispose an accessible object.
     * <p>
     * <b>IMPORTANT:</b> This method is <em>not</em> part of the public
     * API for <code>Accessible</code>. It is marked public only so that it
     * can be shared within the packages provided by DWT. It is not
     * available on all platforms, and should never be called from
     * application code.
     * </p>
     */
    public void internal_dispose_Accessible() {
        if (actionNames !is null) actionNames.release();
        actionNames = null;
        if (attributeNames !is null) attributeNames.release();
        attributeNames = null;
        if (parameterizedAttributeNames !is null) parameterizedAttributeNames.release();
        parameterizedAttributeNames = null;        
        
        foreach (childDelegate ; children)
            childDelegate.internal_dispose_SWTAccessibleDelegate();
        
        children.clear();
    }
    
    cocoa.id getExpandedAttribute(int childID) {
        // TODO: May need to expand the API so the combo box state can be reported.
        return NSNumber.numberWithBool(false);
    }
    
    cocoa.id getHelpAttribute (int childID) {
        cocoa.id returnValue = null;
        AccessibleEvent event = new AccessibleEvent(this);
        event.childID = childID;
        for (int i = 0; i < accessibleListeners.size(); i++) {
            AccessibleListener listener = accessibleListeners.elementAt(i);
            listener.getHelp(event);
        }
        
        if (event.result !is null) {
            returnValue = NSString.stringWith(event.result);
        }
        
        return returnValue;
    }
    
    NSString getRoleAttribute(int childID) {
        NSString returnValue = null;
        AccessibleControlEvent event = new AccessibleControlEvent(this);
        event.childID = childID;
        event.detail = -1;
        for (int i = 0; i < accessibleControlListeners.size(); i++) {
            AccessibleControlListener listener = accessibleControlListeners.elementAt(i);
            listener.getRole(event);
        }
        if (event.detail !is -1) {
            String appRole = roleToOs (event.detail);
            int index = dwt.dwthelper.utils.indexOf(appRole, ':');
            if (index !is -1) appRole = appRole.substring(0, index);
            returnValue = NSString.stringWith(appRole);
        }
        
        return returnValue;
    }
    
    cocoa.id getSubroleAttribute (int childID) {
        cocoa.id returnValue = null;
        AccessibleControlEvent event = new AccessibleControlEvent(this);
        event.childID = childID;
        event.detail = -1;
        for (int i = 0; i < accessibleControlListeners.size(); i++) {
            AccessibleControlListener listener = accessibleControlListeners.elementAt(i);
            listener.getRole(event);
        }
        if (event.detail !is -1) {
            String appRole = roleToOs (event.detail);
            int index = dwt.dwthelper.utils.indexOf(appRole, ':');
            if (index !is -1) {
                appRole = appRole.substring(index + 1);
                returnValue = NSString.stringWith(appRole);
            }
        }
        return returnValue;
    }
    
    cocoa.id getRoleDescriptionAttribute (int childID) {
        cocoa.id returnValue = null;
        AccessibleControlEvent event = new AccessibleControlEvent(this);
        event.childID = childID;
        event.detail = -1;
        for (int i = 0; i < accessibleControlListeners.size(); i++) {
            AccessibleControlListener listener = accessibleControlListeners.elementAt(i);
            listener.getRole(event);
        }
        if (event.detail !is -1) {
            String appRole = roleToOs (event.detail);
            String appSubrole = null;
            int index = dwt.dwthelper.utils.indexOf(appRole, ':');
            if (index !is -1) {
                appSubrole = appRole.substring(index + 1);
                appRole = appRole.substring(0, index);
            }
            NSString nsAppRole = NSString.stringWith(appRole);
            NSString nsAppSubrole = null;
            
            if (appSubrole !is null) nsAppSubrole = NSString.stringWith(appSubrole);
            returnValue = new NSString(OS.NSAccessibilityRoleDescription (((nsAppRole !is null) ? nsAppRole.id : null), (nsAppSubrole !is null) ? nsAppSubrole.id : null));
        }
        return returnValue;
    }
    
    cocoa.id getTitleAttribute (int childID) {
        
        cocoa.id returnValue = null;//NSString.stringWith("");
        
        /*
         * Feature of the Macintosh.  The text of a Label is returned in its value,
         * not its title, so ensure that the role is not Label before asking for the title.
         */
        AccessibleControlEvent roleEvent = new AccessibleControlEvent(this);
        roleEvent.childID = childID;
        roleEvent.detail = -1;
        for (int i = 0; i < accessibleControlListeners.size(); i++) {
            AccessibleControlListener listener = accessibleControlListeners.elementAt(i);
            listener.getRole(roleEvent);
        }
        if (roleEvent.detail !is ACC.ROLE_LABEL) {
            AccessibleEvent event = new AccessibleEvent(this);
            event.childID = childID;
            event.result = null;
            for (int i = 0; i < accessibleListeners.size(); i++) {
                AccessibleListener listener = accessibleListeners.elementAt(i);
                listener.getName(event);
            }
            
            if (event.result !is null)
                returnValue = NSString.stringWith(event.result);
        }
        return returnValue;
    }
    
    cocoa.id getValueAttribute (int childID) {
        cocoa.id returnValue = null;
        AccessibleControlEvent event = new AccessibleControlEvent(this);
        event.childID = childID;
        event.detail = -1;
        event.result = null; //TODO: could pass the OS value to the app
        for (int i = 0; i < accessibleControlListeners.size(); i++) {
            AccessibleControlListener listener = accessibleControlListeners.elementAt(i);
            listener.getRole(event);
            listener.getValue(event);
        }
        int role = event.detail;
        String value = event.result;
        
        switch (role) {
            case ACC.ROLE_RADIOBUTTON: // 1 = on, 0 = off
            case ACC.ROLE_CHECKBUTTON: // 1 = checked, 0 = unchecked, 2 = mixed
            case ACC.ROLE_SCROLLBAR: // numeric value representing the position of the scroller
            case ACC.ROLE_SLIDER: // the value associated with the position of the slider thumb
            case ACC.ROLE_PROGRESSBAR: // the value associated with the fill level of the progress bar
                if (value !is null) {
                    try {
                        int number = Integer.parseInt(value);
                        returnValue = NSNumber.numberWithInt(number);
                    } catch (NumberFormatException ex) {
                        if (value.equalsIgnoreCase("true")) {
                            returnValue = NSNumber.numberWithBool(true);
                        } else if (value.equalsIgnoreCase("false")) {
                            returnValue = NSNumber.numberWithBool(false);
                        }
                    }
                } else {
                    returnValue = NSNumber.numberWithBool(false);
                }
                break;
            case ACC.ROLE_TABFOLDER: // the accessibility object representing the currently selected tab item
            case ACC.ROLE_TABITEM:  // 1 = selected, 0 = not selected
                AccessibleControlEvent ace = new AccessibleControlEvent(this);
                ace.childID = -4;
                for (int i = 0; i < accessibleControlListeners.size(); i++) {
                    AccessibleControlListener listener = accessibleControlListeners.elementAt(i);
                    listener.getSelection(ace);
                }
                if (ace.childID >= ACC.CHILDID_SELF) {
                    if (role is ACC.ROLE_TABITEM) {
                        returnValue = NSNumber.numberWithBool(ace.childID is childID);
                    } else {
                        returnValue = new cocoa.id(OS.NSAccessibilityUnignoredAncestor(childIDToOs(ace.childID).id));
                    }
                } else {
                    returnValue = NSNumber.numberWithBool(false);               
                }
                break;
            case ACC.ROLE_COMBOBOX: // text of the currently selected item
            case ACC.ROLE_TEXT: // text in the text field
                if (value !is null) returnValue = NSString.stringWith(value);
                break;
            case ACC.ROLE_LABEL: // text in the label
                /* On a Mac, the 'value' of a label is the same as the 'name' of the label. */
                AccessibleEvent e = new AccessibleEvent(this);
                e.childID = childID;
                e.result = null;
                for (int i = 0; i < accessibleListeners.size(); i++) {
                    AccessibleListener listener = accessibleListeners.elementAt(i);
                    listener.getName(e);
                }
                if (e.result !is null) {
                    returnValue = NSString.stringWith(e.result);
                } else {
                    if (value !is null) returnValue = NSString.stringWith(value);
                }
                break;
        }
        
        return returnValue;
    }
    
    cocoa.id getEnabledAttribute (int childID) {
        AccessibleControlEvent event = new AccessibleControlEvent(this);
        event.detail = -1;
        for (int i = 0; i < accessibleControlListeners.size(); i++) {
            AccessibleControlListener listener = accessibleControlListeners.elementAt(i);
            listener.getState(event);
        }
        
        return NSNumber.numberWithBool(control.isEnabled());
    }
    
    cocoa.id getFocusedAttribute (int childID) {
        AccessibleControlEvent event = new AccessibleControlEvent(this);
        event.childID = ACC.CHILDID_MULTIPLE; // set to invalid value, to test if the application sets it in getFocus()
        event.accessible = null;
        for (int i = 0; i < accessibleControlListeners.size(); i++) {
            AccessibleControlListener listener = accessibleControlListeners.elementAt(i);
            listener.getFocus(event);
        }
        
        /* The application can optionally answer an accessible. */
        // FIXME:
        //      if (event.accessible !is null) {
        //          bool hasFocus = (event.accessible.childID is childID) && (event.accessible.control is this.control);
        //          return NSNumber.numberWithBool(hasFocus);
        //      }
        
        /* Or the application can answer a valid child ID, including CHILDID_SELF and CHILDID_NONE. */
        if (event.childID is ACC.CHILDID_SELF) {
            bool hasFocus = (event.childID is childID);
            return NSNumber.numberWithBool(hasFocus);
        }
        if (event.childID is ACC.CHILDID_NONE) {
            return NSNumber.numberWithBool(false);
        }
        if (event.childID !is ACC.CHILDID_MULTIPLE) {
            /* Other valid childID. */
            return NSNumber.numberWithBool(event.childID is childID);
        }
        
        // Invalid childID at this point means the application did not implement getFocus, so 
        // let the default handler return the native focus.
        bool hasFocus = (this.control.view.window().firstResponder() is control.view);
        return NSNumber.numberWithBool(hasFocus);
    }
    
    cocoa.id getParentAttribute (int childID) {
        // Returning null here means 'let Cocoa figure it out.'
        if (childID is ACC.CHILDID_SELF)
            return null;
        else
            return new cocoa.id(OS.NSAccessibilityUnignoredAncestor(control.view.id));
    }
    
    cocoa.id getChildrenAttribute (int childID) {
        cocoa.id returnValue = null;
        if (childID is ACC.CHILDID_SELF) {
            AccessibleControlEvent event = new AccessibleControlEvent(this);
            event.childID = childID;
            event.detail = -1; // set to impossible value to test if app resets
            for (int i = 0; i < accessibleControlListeners.size(); i++) {
                AccessibleControlListener listener = accessibleControlListeners.elementAt(i);
                listener.getChildCount(event);
            }
            if (event.detail > 0) {
                for (int i = 0; i < accessibleControlListeners.size(); i++) {
                    AccessibleControlListener listener = accessibleControlListeners.elementAt(i);
                    listener.getChildren(event);
                }
                Object [] appChildren = event.children;
                if (appChildren !is null && appChildren.length > 0) {
                    /* return an NSArray of NSAccessible objects. */
                    NSMutableArray childArray = NSMutableArray.arrayWithCapacity(appChildren.length);
                    
                    for (int i = 0; i < appChildren.length; i++) {
                        Object child = appChildren[i];
                        if (cast(Integer) child) {
                            cocoa.id accChild = childIDToOs((cast(Integer)child).intValue());                         
                            childArray.addObject(accChild);
                        } else {
                            childArray.addObject((cast(Accessible)child).control.view);
                        }
                    }
                    
                    returnValue = new cocoa.id(OS.NSAccessibilityUnignoredChildren(childArray.id));
                }
            }
        } else {
            // Lightweight children have no children of their own.
            // Don't return null if there are no children -- always return an empty array.
            returnValue = NSArray.array();
        }
        
        // Returning null here means we want the control itself to determine its children. If the accessible listener
        // implemented getChildCount/getChildren, references to those objects would have been returned above.
        return returnValue;
    }
    
    cocoa.id getTabsAttribute (int childID) {
        cocoa.id returnValue = null;
        if (childID is ACC.CHILDID_SELF) {
            AccessibleControlEvent event = new AccessibleControlEvent(this);
            event.childID = childID;
            event.detail = -1; // set to impossible value to test if app resets
            for (int i = 0; i < accessibleControlListeners.size(); i++) {
                AccessibleControlListener listener = accessibleControlListeners.elementAt(i);
                listener.getChildCount(event);
            }
            if (event.detail > 0) {
                for (int i = 0; i < accessibleControlListeners.size(); i++) {
                    AccessibleControlListener listener = accessibleControlListeners.elementAt(i);
                    listener.getChildren(event);
                }
                Object [] appChildren = event.children;
                if (appChildren !is null && appChildren.length > 0) {
                    /* return an NSArray of NSAccessible objects. */
                    NSMutableArray childArray = NSMutableArray.arrayWithCapacity(appChildren.length);
                    
                    for (int i = 0; i < appChildren.length; i++) {
                        Object child = appChildren[i];
                        if (cast(Integer)child) {
                            int subChildID = (cast(Integer)child).intValue();
                            event.childID = subChildID;
                            event.detail = -1;
                            for (int j = 0; j < accessibleControlListeners.size(); j++) {
                                AccessibleControlListener listener = accessibleControlListeners.elementAt(j);
                                listener.getRole(event);
                            }
                            
                            if (event.detail is ACC.ROLE_TABITEM) {
                                cocoa.id accChild = childIDToOs((cast(Integer)child).intValue());                         
                                childArray.addObject(accChild);
                            }
                        } else {
                            childArray.addObject((cast(Accessible)child).control.view);
                        }
                    }
                    
                    returnValue = new cocoa.id(OS.NSAccessibilityUnignoredChildren(childArray.id));
                }
            }
        } else {
            // Lightweight children have no children of their own.
            // Don't return null if there are no children -- always return an empty array.
            returnValue = NSArray.array();
        }
        
        // Returning null here means we want the control itself to determine its children. If the accessible listener
        // implemented getChildCount/getChildren, references to those objects would have been returned above.
        return returnValue;
    }
    
    cocoa.id getWindowAttribute (int childID) {
        return control.view.window();
    }
    
    cocoa.id getTopLevelUIElementAttribute (int childID) {
        return control.view.window();
    }
    
    cocoa.id getPositionAttribute (int childID) {
        cocoa.id returnValue = null;
        AccessibleControlEvent event = new AccessibleControlEvent(this);
        event.childID = childID;
        event.width = -1;
        
        for (int i = 0; i < accessibleControlListeners.size(); i++) {
            AccessibleControlListener listener = accessibleControlListeners.elementAt(i);
            listener.getLocation(event);
        }
        
        dwt.widgets.Monitor.Monitor primaryMonitor = Display.getCurrent().getPrimaryMonitor();
        
        NSPoint osPositionAttribute = NSPoint ();
        if (event.width !is -1) {
            // The point returned is the lower-left coordinate of the widget in lower-left relative screen coordinates.
            osPositionAttribute.x = event.x;
            osPositionAttribute.y = primaryMonitor.getBounds().height - event.y - event.height;
            returnValue = NSValue.valueWithPoint(osPositionAttribute);
        } else {
            if (childID !is ACC.CHILDID_SELF) {
                Point pt = null;
                Rectangle location = control.getBounds();
                
                if (control.getParent() !is null)
                    pt = control.getParent().toDisplay(location.x, location.y);
                else 
                    pt = (cast(Shell)control).toDisplay(location.x, location.y);
                
                osPositionAttribute.x = pt.x;
                osPositionAttribute.y = pt.y;
                returnValue = NSValue.valueWithPoint(osPositionAttribute);
            }
        }
        
        return returnValue;
    }
    
    cocoa.id getSizeAttribute (int childID) {
        cocoa.id returnValue = null;
        AccessibleControlEvent event = new AccessibleControlEvent(this);
        event.childID = childID;
        event.width = -1;
        
        for (int i = 0; i < accessibleControlListeners.size(); i++) {
            AccessibleControlListener listener = accessibleControlListeners.elementAt(i);
            listener.getLocation(event);
        }
        
        NSSize controlSize = NSSize ();
        if (event.width !is -1) {
            controlSize.width = event.width;
            controlSize.height = event.height;
            returnValue = NSValue.valueWithSize(controlSize);
        } else {
            if (childID !is ACC.CHILDID_SELF) {
                controlSize.width = controlSize.height = 0;
                returnValue = NSValue.valueWithSize(controlSize);
            }
        }
        
        return returnValue;
    }
    
    cocoa.id getDescriptionAttribute (int childID) {
        AccessibleEvent event = new AccessibleEvent(this);
        event.childID = childID;
        event.result = null;
        cocoa.id returnValue = null;
        for (int i = 0; i < accessibleListeners.size(); i++) {
            AccessibleListener listener = accessibleListeners.elementAt(i);
            listener.getDescription(event);
        }
        
        returnValue = (event.result !is null ? NSString.stringWith(event.result) : null);
        
        // If no description was provided, try the name.
        if (returnValue is null) {
            if (cast(Composite) control) returnValue = NSString.stringWith("");
        }
        
        return returnValue;
    }
    
    cocoa.id getInsertionPointLineNumberAttribute (int childID) {
        cocoa.id returnValue = null;
        AccessibleControlEvent controlEvent = new AccessibleControlEvent(this);
        controlEvent.childID = childID;
        controlEvent.result = null;
        for (int i = 0; i < accessibleControlListeners.size(); i++) {
            AccessibleControlListener listener = accessibleControlListeners.elementAt(i);
            listener.getValue(controlEvent);
        }
        AccessibleTextEvent textEvent = new AccessibleTextEvent(this);
        textEvent.childID = childID;
        textEvent.offset = -1;
        for (int i = 0; i < accessibleTextListeners.size(); i++) {
            AccessibleTextListener listener = accessibleTextListeners.elementAt(i);
            listener.getCaretOffset(textEvent);
        }
        if (controlEvent.result !is null && textEvent.offset !is -1) {
            int lineNumber = lineNumberForOffset (controlEvent.result, textEvent.offset);
            returnValue = NSNumber.numberWithInt(lineNumber);
        }
        return returnValue;
    }
    
    cocoa.id getNumberOfCharactersAttribute (int childID) {
        cocoa.id returnValue = null;
        AccessibleControlEvent event = new AccessibleControlEvent(this);
        event.childID = childID;
        event.result = null;
        for (int i = 0; i < accessibleControlListeners.size(); i++) {
            AccessibleControlListener listener = accessibleControlListeners.elementAt(i);
            listener.getValue(event);
        }
        String appValue = event.result;
        if (appValue !is null) {
            returnValue = NSNumber.numberWithInt(appValue.length());
        }
        return returnValue;
    }
    
    cocoa.id getRangeForLineParameterizedAttribute (cocoa.id parameter, int childID) {
        cocoa.id returnValue = null;
        
        // The parameter is an NSNumber with the line number.
        NSNumber lineNumberObj = new NSNumber(parameter.id);        
        int lineNumber = lineNumberObj.intValue();
        System.out_.println("Line number = " ~ Integer.toString(lineNumber));
        AccessibleControlEvent event = new AccessibleControlEvent(this);
        event.childID = childID;
        event.result = null;
        for (int i = 0; i < accessibleControlListeners.size(); i++) {
            AccessibleControlListener listener = accessibleControlListeners.elementAt(i);
            listener.getValue(event);
        }
        if (event.result !is null) {
            NSRange range = rangeForLineNumber (lineNumber, event.result);
            if (range.location !is -1) {
                returnValue = NSValue.valueWithRange(range);
            }
        }
        return returnValue;
    }
    
    cocoa.id getSelectedTextAttribute (int childID) {
        cocoa.id returnValue = NSString.stringWith("");
        AccessibleTextEvent event = new AccessibleTextEvent(this);
        event.childID = childID;
        event.offset = -1;
        event.length = -1;
        for (int i = 0; i < accessibleTextListeners.size(); i++) {
            AccessibleTextListener listener = accessibleTextListeners.elementAt(i);
            listener.getSelectionRange(event);
        }
        int offset = event.offset;
        int length = event.length;
        if (offset !is -1 && length !is -1 && length !is 0) {  // TODO: do we need the && length !is 0 ?
            AccessibleControlEvent event2 = new AccessibleControlEvent(this);
            event2.childID = event.childID;
            event2.result = null;
            for (int i = 0; i < accessibleControlListeners.size(); i++) {
                AccessibleControlListener listener = accessibleControlListeners.elementAt(i);
                listener.getValue(event2);
            }
            String appValue = event2.result;
            if (appValue !is null) {
                returnValue = NSString.stringWith(appValue.substring(offset, offset + length));
            }
        }
        return returnValue;
    }
    
    cocoa.id getSelectedTextRangeAttribute (int childID) {
        cocoa.id returnValue = null;
        AccessibleTextEvent event = new AccessibleTextEvent(this);
        event.childID = childID;
        event.offset = -1;
        event.length = 0;
        for (int i = 0; i < accessibleTextListeners.size(); i++) {
            AccessibleTextListener listener = accessibleTextListeners.elementAt(i);
            listener.getSelectionRange(event);
        }
        if (event.offset !is -1) {
            NSRange range = NSRange();
            range.location = event.offset;
            range.length = event.length;
            returnValue = NSValue.valueWithRange(range);
        }
        return returnValue;
    }
    
    cocoa.id getStringForRangeAttribute (cocoa.id parameter, int childID) {
        cocoa.id returnValue = null;
        
        // Parameter is an NSRange wrapped in an NSValue. 
        NSValue parameterObject = new NSValue(parameter.id);
        NSRange range = parameterObject.rangeValue();       
        AccessibleControlEvent event = new AccessibleControlEvent(this);
        event.childID = childID;
        event.result = null;
        for (int i = 0; i < accessibleControlListeners.size(); i++) {
            AccessibleControlListener listener = accessibleControlListeners.elementAt(i);
            listener.getValue(event);
        }
        String appValue = event.result;
        
        if (appValue !is null) {
            returnValue = NSString.stringWith(appValue.substring(range.location, range.location + range.length));
        }
        
        return returnValue;
    }
    
    cocoa.id getSelectedTextRangesAttribute (int childID) {
        NSMutableArray returnValue = null; 
        AccessibleTextEvent event = new AccessibleTextEvent(this);
        event.childID = childID;
        event.offset = -1;
        event.length = 0;
        
        for (int i = 0; i < accessibleTextListeners.size(); i++) {
            AccessibleTextListener listener = accessibleTextListeners.elementAt(i);
            listener.getSelectionRange(event);
        }
        
        if (event.offset !is -1) {
            returnValue = NSMutableArray.arrayWithCapacity(1);
            NSRange range = NSRange();
            range.location = event.offset;
            range.length = event.length;
            returnValue.addObject(NSValue.valueWithRange(range));
        }
        
        return returnValue;
    }
    
    cocoa.id getVisibleCharacterRangeAttribute (int childID) {
        AccessibleControlEvent event = new AccessibleControlEvent(this);
        event.childID = childID;
        event.result = null;
        for (int i = 0; i < accessibleControlListeners.size(); i++) {
            AccessibleControlListener listener = accessibleControlListeners.elementAt(i);
            listener.getValue(event);
        }
        
        NSRange range = NSRange();
        
        if (event.result !is null) {
            range.location = 0;
            range.length = event.result.length();
        } else {
            return null;
            //          range.location = range.length = 0;
        }
        
        return NSValue.valueWithRange(range);
    }
    
    int lineNumberForOffset (String text, int offset) {
        int lineNumber = 1;
        int length = text.length();
        for (int i = 0; i < offset; i++) {
            switch (text.charAt (i)) {
                case '\r': 
                    if (i + 1 < length) {
                        if (text.charAt (i + 1) is '\n') ++i;
                    }
                    // FALL THROUGH
                case '\n':
                    lineNumber++;
            }
        }
        return lineNumber;
    }
    
    NSRange rangeForLineNumber (int lineNumber, String text) {
        NSRange range = NSRange();
        range.location = -1;
        int line = 1;
        int count = 0;
        int length = text.length ();
        for (int i = 0; i < length; i++) {
            if (line is lineNumber) {
                if (count is 0) {
                    range.location = i;
                }
                count++;
            }
            if (line > lineNumber) break;
            switch (text.charAt (i)) {
                case '\r': 
                    if (i + 1 < length && text.charAt (i + 1) is '\n') i++;
                    // FALL THROUGH
                case '\n':
                    line++;
            }
        }
        range.length = count;
        return range;
    }
    
    /**
     * Removes the listener from the collection of listeners who will
     * be notified when an accessible client asks for certain strings,
     * such as name, description, help, or keyboard shortcut.
     *
     * @param listener the listener that should no longer be notified when the receiver
     * is asked for a name, description, help, or keyboard shortcut string
     *
     * @exception IllegalArgumentException <ul>
     *    <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
     * </ul>
     * @exception DWTException <ul>
     *    <li>ERROR_WIDGET_DISPOSED - if the receiver's control has been disposed</li>
     *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver's control</li>
     * </ul>
     *
     * @see AccessibleListener
     * @see #addAccessibleListener
     */
    public void removeAccessibleListener(AccessibleListener listener) {
        checkWidget();
        if (listener is null) DWT.error(DWT.ERROR_NULL_ARGUMENT);
        accessibleListeners.removeElement(listener);
    }
    
    /**
     * Removes the listener from the collection of listeners who will
     * be notified when an accessible client asks for custom control
     * specific information.
     *
     * @param listener the listener that should no longer be notified when the receiver
     * is asked for custom control specific information
     *
     * @exception IllegalArgumentException <ul>
     *    <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
     * </ul>
     * @exception DWTException <ul>
     *    <li>ERROR_WIDGET_DISPOSED - if the receiver's control has been disposed</li>
     *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver's control</li>
     * </ul>
     *
     * @see AccessibleControlListener
     * @see #addAccessibleControlListener
     */
    public void removeAccessibleControlListener(AccessibleControlListener listener) {
        checkWidget();
        if (listener is null) DWT.error(DWT.ERROR_NULL_ARGUMENT);
        accessibleControlListeners.removeElement(listener);
    }
    
    /**
     * Removes the listener from the collection of listeners who will
     * be notified when an accessible client asks for custom text control
     * specific information.
     *
     * @param listener the listener that should no longer be notified when the receiver
     * is asked for custom text control specific information
     *
     * @exception IllegalArgumentException <ul>
     *    <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
     * </ul>
     * @exception DWTException <ul>
     *    <li>ERROR_WIDGET_DISPOSED - if the receiver's control has been disposed</li>
     *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver's control</li>
     * </ul>
     *
     * @see AccessibleTextListener
     * @see #addAccessibleTextListener
     * 
     * @since 3.0
     */
    public void removeAccessibleTextListener (AccessibleTextListener listener) {
        checkWidget ();
        if (listener is null) DWT.error (DWT.ERROR_NULL_ARGUMENT);
        accessibleTextListeners.removeElement (listener);
    }
    
    static NSArray retainedAutoreleased(NSArray inObject) {
        cocoa.id temp = inObject.retain();
        cocoa.id temp2 = (new NSObject(temp.id)).autorelease();
        return new NSArray(temp2.id);
    }
    
    /**
     * Sends a message to accessible clients that the child selection
     * within a custom container control has changed.
     *
     * @exception DWTException <ul>
     *    <li>ERROR_WIDGET_DISPOSED - if the receiver's control has been disposed</li>
     *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver's control</li>
     * </ul>
     * 
     * @since 3.0
     */
    public void selectionChanged () {
        checkWidget();
        OS.NSAccessibilityPostNotification(control.view.id, OS.NSAccessibilitySelectedChildrenChangedNotification.id);
    }
    
    /**
     * Sends a message to accessible clients indicating that the focus
     * has changed within a custom control.
     *
     * @param childID an identifier specifying a child of the control
     * 
     * @exception DWTException <ul>
     *    <li>ERROR_WIDGET_DISPOSED - if the receiver's control has been disposed</li>
     *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver's control</li>
     * </ul>
     */
    public void setFocus(int childID) {
        checkWidget();
        OS.NSAccessibilityPostNotification(control.view.id, OS.NSAccessibilityFocusedUIElementChangedNotification.id);
    }
    
    /**
     * Sends a message to accessible clients that the text
     * caret has moved within a custom control.
     *
     * @param index the new caret index within the control
     * 
     * @exception DWTException <ul>
     *    <li>ERROR_WIDGET_DISPOSED - if the receiver's control has been disposed</li>
     *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver's control</li>
     * </ul>
     *
     * @since 3.0
     */
    public void textCaretMoved (int index) {
        checkWidget();
        OS.NSAccessibilityPostNotification(control.view.id, OS.NSAccessibilitySelectedTextChangedNotification.id);
    }
    
    /**
     * Sends a message to accessible clients that the text
     * within a custom control has changed.
     *
     * @param type the type of change, one of <code>ACC.NOTIFY_TEXT_INSERT</code>
     * or <code>ACC.NOTIFY_TEXT_DELETE</code>
     * @param startIndex the text index within the control where the insertion or deletion begins
     * @param length the non-negative length in characters of the insertion or deletion
     *
     * @exception DWTException <ul>
     *    <li>ERROR_WIDGET_DISPOSED - if the receiver's control has been disposed</li>
     *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver's control</li>
     * </ul>
     * 
     * @see ACC#TEXT_INSERT
     * @see ACC#TEXT_DELETE
     * 
     * @since 3.0
     */
    public void textChanged (int type, int startIndex, int length) {
        checkWidget();
        OS.NSAccessibilityPostNotification(control.view.id, OS.NSAccessibilityValueChangedNotification.id);
    }
    
    /**
     * Sends a message to accessible clients that the text
     * selection has changed within a custom control.
     *
     * @exception DWTException <ul>
     *    <li>ERROR_WIDGET_DISPOSED - if the receiver's control has been disposed</li>
     *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver's control</li>
     * </ul>
     *
     * @since 3.0
     */
    public void textSelectionChanged () {
        checkWidget();
        OS.NSAccessibilityPostNotification(control.view.id, OS.NSAccessibilitySelectedTextChangedNotification.id);
    }
    
    cocoa.id childIDToOs(int childID) {
        if (childID is ACC.CHILDID_SELF) {
            return control.view;
        }
        
        /* Check cache for childID, if found, return corresponding osChildID. */
        SWTAccessibleDelegate childRef = children[childID];
        
        if (childRef is null) {
            childRef = new SWTAccessibleDelegate(this, childID);
            children.put(childID, childRef);
        }
        
        return childRef;
    }
    
    NSString concatStringsAsRole(NSString str1, NSString str2) {
        NSString returnValue = str1;
        returnValue = returnValue.stringByAppendingString(NSString.stringWith(":"));
        returnValue = returnValue.stringByAppendingString(str2);
        return returnValue;
    }   
    
    String roleToOs(int role) {
        NSString nsReturnValue = null; //OS.NSAccessibilityUnknownRole;
        
        switch (role) {
            case ACC.ROLE_CLIENT_AREA: nsReturnValue = OS.NSAccessibilityGroupRole; break;
            case ACC.ROLE_WINDOW: nsReturnValue = OS.NSAccessibilityWindowRole; break;
            case ACC.ROLE_MENUBAR: nsReturnValue = OS.NSAccessibilityMenuBarRole; break;
            case ACC.ROLE_MENU: nsReturnValue = OS.NSAccessibilityMenuRole; break;
            case ACC.ROLE_MENUITEM: nsReturnValue = OS.NSAccessibilityMenuItemRole; break;
            case ACC.ROLE_SEPARATOR: nsReturnValue = OS.NSAccessibilitySplitterRole; break;
            case ACC.ROLE_TOOLTIP: nsReturnValue = OS.NSAccessibilityHelpTagRole; break;
            case ACC.ROLE_SCROLLBAR: nsReturnValue = OS.NSAccessibilityScrollBarRole; break;
            case ACC.ROLE_DIALOG: nsReturnValue = concatStringsAsRole(OS.NSAccessibilityWindowRole, OS.NSAccessibilityDialogSubrole); break;
            case ACC.ROLE_LABEL: nsReturnValue = OS.NSAccessibilityStaticTextRole; break;
            case ACC.ROLE_PUSHBUTTON: nsReturnValue = OS.NSAccessibilityButtonRole; break;
            case ACC.ROLE_CHECKBUTTON: nsReturnValue = OS.NSAccessibilityCheckBoxRole; break;
            case ACC.ROLE_RADIOBUTTON: nsReturnValue = OS.NSAccessibilityRadioButtonRole; break;
            case ACC.ROLE_COMBOBOX: nsReturnValue = OS.NSAccessibilityComboBoxRole; break;
            case ACC.ROLE_TEXT: {
                int style = control.getStyle();
                
                if ((style & DWT.MULTI) !is 0) {
                    nsReturnValue = OS.NSAccessibilityTextAreaRole;
                } else {
                    nsReturnValue = OS.NSAccessibilityTextFieldRole;
                }
                
                break;
            }
            case ACC.ROLE_TOOLBAR: nsReturnValue = OS.NSAccessibilityToolbarRole; break;
            case ACC.ROLE_LIST: nsReturnValue = OS.NSAccessibilityOutlineRole; break;
            case ACC.ROLE_LISTITEM: nsReturnValue = OS.NSAccessibilityStaticTextRole; break;
            case ACC.ROLE_TABLE: nsReturnValue = OS.NSAccessibilityTableRole; break;
            case ACC.ROLE_TABLECELL: nsReturnValue = concatStringsAsRole(OS.NSAccessibilityRowRole, OS.NSAccessibilityTableRowSubrole); break;
            case ACC.ROLE_TABLECOLUMNHEADER: nsReturnValue = OS.NSAccessibilitySortButtonRole; break;
            case ACC.ROLE_TABLEROWHEADER: nsReturnValue = concatStringsAsRole(OS.NSAccessibilityRowRole, OS.NSAccessibilityTableRowSubrole); break;
            case ACC.ROLE_TREE: nsReturnValue = OS.NSAccessibilityOutlineRole; break;
            case ACC.ROLE_TREEITEM: nsReturnValue = concatStringsAsRole(OS.NSAccessibilityOutlineRole, OS.NSAccessibilityOutlineRowSubrole); break;
            case ACC.ROLE_TABFOLDER: nsReturnValue = OS.NSAccessibilityTabGroupRole; break;
            case ACC.ROLE_TABITEM: nsReturnValue = OS.NSAccessibilityRadioButtonRole; break;
            case ACC.ROLE_PROGRESSBAR: nsReturnValue = OS.NSAccessibilityProgressIndicatorRole; break;
            case ACC.ROLE_SLIDER: nsReturnValue = OS.NSAccessibilitySliderRole; break;
            case ACC.ROLE_LINK: nsReturnValue = OS.NSAccessibilityLinkRole; break;
        }
        
        return nsReturnValue.getString();
    }
    
    int osToRole(NSString osRole) {
        if (osRole is null) return 0;
        if (osRole.isEqualToString(OS.NSAccessibilityWindowRole)) return ACC.ROLE_WINDOW;
        if (osRole.isEqualToString(OS.NSAccessibilityMenuBarRole)) return ACC.ROLE_MENUBAR;
        if (osRole.isEqualToString(OS.NSAccessibilityMenuRole)) return ACC.ROLE_MENU;
        if (osRole.isEqualToString(OS.NSAccessibilityMenuItemRole)) return ACC.ROLE_MENUITEM;
        if (osRole.isEqualToString(OS.NSAccessibilitySplitterRole)) return ACC.ROLE_SEPARATOR;
        if (osRole.isEqualToString(OS.NSAccessibilityHelpTagRole)) return ACC.ROLE_TOOLTIP;
        if (osRole.isEqualToString(OS.NSAccessibilityScrollBarRole)) return ACC.ROLE_SCROLLBAR;
        if (osRole.isEqualToString(OS.NSAccessibilityScrollAreaRole)) return ACC.ROLE_LIST;
        if (osRole.isEqualToString(concatStringsAsRole(OS.NSAccessibilityWindowRole, OS.NSAccessibilityDialogSubrole))) return ACC.ROLE_DIALOG;
        if (osRole.isEqualToString(concatStringsAsRole(OS.NSAccessibilityWindowRole, OS.NSAccessibilitySystemDialogSubrole))) return ACC.ROLE_DIALOG;
        if (osRole.isEqualToString(OS.NSAccessibilityStaticTextRole)) return ACC.ROLE_LABEL;
        if (osRole.isEqualToString(OS.NSAccessibilityButtonRole)) return ACC.ROLE_PUSHBUTTON;
        if (osRole.isEqualToString(OS.NSAccessibilityCheckBoxRole)) return ACC.ROLE_CHECKBUTTON;
        if (osRole.isEqualToString(OS.NSAccessibilityRadioButtonRole)) return ACC.ROLE_RADIOBUTTON;
        if (osRole.isEqualToString(OS.NSAccessibilityComboBoxRole)) return ACC.ROLE_COMBOBOX;
        if (osRole.isEqualToString(OS.NSAccessibilityTextFieldRole)) return ACC.ROLE_TEXT;
        if (osRole.isEqualToString(OS.NSAccessibilityTextAreaRole)) return ACC.ROLE_TEXT;
        if (osRole.isEqualToString(OS.NSAccessibilityToolbarRole)) return ACC.ROLE_TOOLBAR;
        if (osRole.isEqualToString(OS.NSAccessibilityListRole)) return ACC.ROLE_LIST;
        if (osRole.isEqualToString(OS.NSAccessibilityTableRole)) return ACC.ROLE_TABLE;
        if (osRole.isEqualToString(OS.NSAccessibilityColumnRole)) return ACC.ROLE_TABLECOLUMNHEADER;
        if (osRole.isEqualToString(concatStringsAsRole(OS.NSAccessibilityButtonRole, OS.NSAccessibilitySortButtonRole))) return ACC.ROLE_TABLECOLUMNHEADER;
        if (osRole.isEqualToString(concatStringsAsRole(OS.NSAccessibilityRowRole, OS.NSAccessibilityTableRowSubrole))) return ACC.ROLE_TABLEROWHEADER;
        if (osRole.isEqualToString(OS.NSAccessibilityOutlineRole)) return ACC.ROLE_TREE;
        if (osRole.isEqualToString(concatStringsAsRole(OS.NSAccessibilityOutlineRole, OS.NSAccessibilityOutlineRowSubrole))) return ACC.ROLE_TREEITEM;
        if (osRole.isEqualToString(OS.NSAccessibilityTabGroupRole)) return ACC.ROLE_TABFOLDER;
        if (osRole.isEqualToString(OS.NSAccessibilityProgressIndicatorRole)) return ACC.ROLE_PROGRESSBAR;
        if (osRole.isEqualToString(OS.NSAccessibilitySliderRole)) return ACC.ROLE_SLIDER;
        if (osRole.isEqualToString(OS.NSAccessibilityLinkRole)) return ACC.ROLE_LINK;
        return ACC.ROLE_CLIENT_AREA;
    }
    
    /* checkWidget was copied from Widget, and rewritten to work in this package */
    void checkWidget () {
        if (!isValidThread ()) DWT.error (DWT.ERROR_THREAD_INVALID_ACCESS);
        if (control.isDisposed ()) DWT.error (DWT.ERROR_WIDGET_DISPOSED);
    }
    
    /* isValidThread was copied from Widget, and rewritten to work in this package */
    bool isValidThread () {
        return control.getDisplay ().getThread () is Thread.getThis ();
    }
    
}