CCombo.java

/*******************************************************************************
 * Copyright (c) 2000, 2019 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *     Paul Pazderski - Bug 349112: allow setting alignment on the text field
 *******************************************************************************/
package org.eclipse.swt.custom;


import java.util.function.*;

import org.eclipse.swt.*;
import org.eclipse.swt.accessibility.*;
import org.eclipse.swt.events.*;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.widgets.*;

/**
 * The CCombo class represents a selectable user interface object
 * that combines a text field and a list and issues notification
 * when an item is selected from the list.
 * <p>
 * CCombo was written to work around certain limitations in the native
 * combo box. Specifically, on win32, the height of a CCombo can be set;
 * attempts to set the height of a Combo are ignored. CCombo can be used
 * anywhere that having the increased flexibility is more important than
 * getting native L&amp;F, but the decision should not be taken lightly.
 * There is no strict requirement that CCombo look or behave the same as
 * the native combo box.
 * </p>
 * <p>
 * Note that although this class is a subclass of <code>Composite</code>,
 * it does not make sense to add children to it, or set a layout on it.
 * </p>
 * <dl>
 * <dt><b>Styles:</b>
 * <dd>BORDER, READ_ONLY, FLAT, LEAD, LEFT, CENTER, TRAIL, RIGHT</dd>
 * <dt><b>Events:</b>
 * <dd>DefaultSelection, Modify, Selection, Verify</dd>
 * </dl>
 *
 * @see <a href="http://www.eclipse.org/swt/snippets/#ccombo">CCombo snippets</a>
 * @see <a href="http://www.eclipse.org/swt/examples.php">SWT Example: CustomControlExample</a>
 * @see <a href="http://www.eclipse.org/swt/">Sample code and further information</a>
 */
public class CCombo extends Composite {

	Text text;
	List list;
	int visibleItemCount = 5;
	Shell popup;
	Button arrow;
	boolean hasFocus;
	Listener listener, filter;
	Color foreground, background;
	Font font;
	Shell _shell;

	static final String PACKAGE_PREFIX = "org.eclipse.swt.custom."; //$NON-NLS-1$

/**
 * Constructs a new instance of this class given its parent
 * and a style value describing its behavior and appearance.
 * <p>
 * The style value is either one of the style constants defined in
 * class <code>SWT</code> which is applicable to instances of this
 * class, or must be built by <em>bitwise OR</em>'ing together
 * (that is, using the <code>int</code> "|" operator) two or more
 * of those <code>SWT</code> style constants. The class description
 * lists the style constants that are applicable to the class.
 * Style bits are also inherited from superclasses.
 * </p>
 *
 * @param parent a widget which will be the parent of the new instance (cannot be null)
 * @param style the style of widget to construct
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the parent is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the parent</li>
 * </ul>
 *
 * @see SWT#BORDER
 * @see SWT#READ_ONLY
 * @see SWT#FLAT
 * @see SWT#LEAD
 * @see SWT#LEFT
 * @see SWT#CENTER
 * @see SWT#RIGHT
 * @see SWT#TRAIL
 * @see Widget#getStyle()
 */
public CCombo (Composite parent, int style) {
	super (parent, style = checkStyle (style));
	_shell = super.getShell ();

	listener = event -> {
		if (isDisposed ()) return;
		if (popup == event.widget) {
			popupEvent (event);
			return;
		}
		if (text == event.widget) {
			textEvent (event);
			return;
		}
		if (list == event.widget) {
			listEvent (event);
			return;
		}
		if (arrow == event.widget) {
			arrowEvent (event);
			return;
		}
		if (CCombo.this == event.widget) {
			comboEvent (event);
			return;
		}
		if (getShell () == event.widget) {
			getDisplay().asyncExec(() -> {
				if (isDisposed ()) return;
				handleFocus (SWT.FocusOut);
			});
		}
	};

	createText(style);

	int arrowStyle = SWT.ARROW | SWT.DOWN;
	if ((style & SWT.FLAT) != 0) arrowStyle |= SWT.FLAT;
	arrow = new Button (this, arrowStyle);
	filter = event -> {
		if (isDisposed ()) return;
		if (event.type == SWT.Selection) {
			if (event.widget instanceof ScrollBar) {
				handleScroll(event);
			}
			return;
		}
		if (event.widget instanceof Control) {
			Shell shell = ((Control)event.widget).getShell ();
			if (shell == CCombo.this.getShell ()) {
				handleFocus (SWT.FocusOut);
			}
		}
	};

	int [] comboEvents = {SWT.Dispose, SWT.FocusIn, SWT.Move, SWT.Resize, SWT.FocusOut};
	for (int comboEvent : comboEvents)
		this.addListener (comboEvent, listener);

	int [] arrowEvents = {SWT.DragDetect, SWT.MouseDown, SWT.MouseEnter, SWT.MouseExit, SWT.MouseHover,
		SWT.MouseMove, SWT.MouseUp, SWT.MouseWheel, SWT.Selection, SWT.FocusIn};
	for (int arrowEvent : arrowEvents)
		arrow.addListener (arrowEvent, listener);

	createPopup(null, -1);
	if ((style & SWT.SIMPLE) == 0) {
		int itemHeight = list.getItemHeight ();
		if (itemHeight != 0) {
			int maxHeight = getMonitor().getClientArea().height / 3;
			visibleItemCount = Math.max(visibleItemCount, maxHeight / itemHeight);
		}
	}

	initAccessible();
}
static int checkStyle (int style) {
	int mask = SWT.BORDER | SWT.READ_ONLY | SWT.FLAT | SWT.LEFT_TO_RIGHT | SWT.RIGHT_TO_LEFT | SWT.LEAD | SWT.CENTER | SWT.TRAIL;
	return SWT.NO_FOCUS | (style & mask);
}
void createText(int comboStyle) {
	String textValue = null, tooltip = null;
	Point selection = null;
	int limit = 0;
	boolean enabled = false, focus = false, editable = false;
	Font font = null;
	Color fg = null, bg = null;
	Menu menu = null;
	if (text != null) {
		textValue = text.getText();
		tooltip = text.getToolTipText();
		selection = text.getSelection();
		limit = text.getTextLimit();
		enabled = text.isEnabled();
		editable = text.getEditable();
		focus = text.isFocusControl();
		font = text.getFont();
		fg = text.getForeground();
		bg = text.getBackground();
		menu = text.getMenu();
		text.dispose();
	}

	int textStyle = SWT.SINGLE;
	if ((comboStyle & SWT.READ_ONLY) != 0) textStyle |= SWT.READ_ONLY;
	if ((comboStyle & SWT.FLAT) != 0) textStyle |= SWT.FLAT;
	textStyle |= comboStyle & (SWT.LEAD | SWT.CENTER | SWT.TRAIL);
	text = new Text (this, textStyle);
	if (textValue != null) {
		text.setText(textValue);
		text.setToolTipText(tooltip);
		if (selection != null) text.setSelection(selection);
		text.setTextLimit(limit);
		text.setEnabled(enabled);
		text.setEditable(editable);
		if (focus) text.setFocus();
		if (font != null && !font.isDisposed()) text.setFont(font);
		if (fg != null && !fg.isDisposed()) text.setForeground(fg);
		if (bg != null && !bg.isDisposed()) text.setBackground(bg);
		if (menu != null && !menu.isDisposed()) text.setMenu(menu);
		internalLayout(true);
	}

	int [] textEvents = {SWT.DefaultSelection, SWT.DragDetect, SWT.KeyDown, SWT.KeyUp, SWT.MenuDetect, SWT.Modify,
			SWT.MouseDown, SWT.MouseUp, SWT.MouseDoubleClick, SWT.MouseEnter, SWT.MouseExit, SWT.MouseHover,
			SWT.MouseMove, SWT.MouseWheel, SWT.Traverse, SWT.FocusIn, SWT.Verify};
	for (int textEvent : textEvents)
		text.addListener (textEvent, listener);
}
/**
 * Adds the argument to the end of the receiver's list.
 * <p>
 * Note: If control characters like '\n', '\t' etc. are used
 * in the string, then the behavior is platform dependent.
 * </p>
 * @param string the new item
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the string is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @see #add(String,int)
 */
public void add (String string) {
	checkWidget();
	if (string == null) SWT.error (SWT.ERROR_NULL_ARGUMENT);
	list.add (string);
}
/**
 * Adds the argument to the receiver's list at the given
 * zero-relative index.
 * <p>
 * Note: To add an item at the end of the list, use the
 * result of calling <code>getItemCount()</code> as the
 * index or use <code>add(String)</code>.
 * </p><p>
 * Also note, if control characters like '\n', '\t' etc. are used
 * in the string, then the behavior is platform dependent.
 * </p>
 *
 * @param string the new item
 * @param index the index for the item
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the string is null</li>
 *    <li>ERROR_INVALID_RANGE - if the index is not between 0 and the number of elements in the list (inclusive)</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @see #add(String)
 */
public void add (String string, int index) {
	checkWidget();
	if (string == null) SWT.error (SWT.ERROR_NULL_ARGUMENT);
	list.add (string, index);
}
/**
 * Adds the listener to the collection of listeners who will
 * be notified when the receiver's text is modified, by sending
 * it one of the messages defined in the <code>ModifyListener</code>
 * interface.
 *
 * @param listener the listener which should be notified
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @see ModifyListener
 * @see #removeModifyListener
 */
public void addModifyListener (ModifyListener listener) {
	addTypedListener(listener, SWT.Modify);
}
/**
 * Adds the listener to the collection of listeners who will
 * be notified when the user changes the receiver's selection, by sending
 * it one of the messages defined in the <code>SelectionListener</code>
 * interface.
 * <p>
 * <code>widgetSelected</code> is called when the combo's list selection changes.
 * <code>widgetDefaultSelected</code> is typically called when ENTER is pressed the combo's text area.
 * </p>
 *
 * @param listener the listener which should be notified when the user changes the receiver's selection
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @see SelectionListener
 * @see #removeSelectionListener
 * @see SelectionEvent
 */
public void addSelectionListener(SelectionListener listener) {
	addTypedListener(listener, SWT.Selection, SWT.DefaultSelection);
}
/**
 * Adds the listener to the collection of listeners who will
 * be notified when the receiver's text is verified, by sending
 * it one of the messages defined in the <code>VerifyListener</code>
 * interface.
 *
 * @param listener the listener which should be notified
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @see VerifyListener
 * @see #removeVerifyListener
 *
 * @since 3.3
 */
public void addVerifyListener (VerifyListener listener) {
	addTypedListener(listener, SWT.Verify);
}

void arrowEvent (Event event) {
	switch (event.type) {
		case SWT.FocusIn: {
			handleFocus (SWT.FocusIn);
			break;
		}
		case SWT.DragDetect:
		case SWT.MouseDown:
		case SWT.MouseUp:
		case SWT.MouseMove:
		case SWT.MouseEnter:
		case SWT.MouseExit:
		case SWT.MouseHover: {
			Point pt = getDisplay ().map (arrow, this, event.x, event.y);
			event.x = pt.x; event.y = pt.y;
			notifyListeners (event.type, event);
			event.type = SWT.None;
			break;
		}
		case SWT.MouseWheel: {
			Point pt = getDisplay ().map (arrow, this, event.x, event.y);
			event.x = pt.x; event.y = pt.y;
			notifyListeners (SWT.MouseWheel, event);
			event.type = SWT.None;
			if (isDisposed ()) break;
			if (!event.doit) break;
			if (event.count != 0) {
				event.doit = false;
				int oldIndex = getSelectionIndex ();
				if (event.count > 0) {
					select (Math.max (oldIndex - 1, 0));
				} else {
					select (Math.min (oldIndex + 1, getItemCount () - 1));
				}
				if (oldIndex != getSelectionIndex ()) {
					Event e = new Event();
					e.time = event.time;
					e.stateMask = event.stateMask;
					notifyListeners (SWT.Selection, e);
				}
				if (isDisposed ()) break;
			}
			break;
		}
		case SWT.Selection: {
			text.setFocus();
			dropDown (!isDropped ());
			break;
		}
	}
}
@Override
protected void checkSubclass () {
	String name = getClass ().getName ();
	int index = name.lastIndexOf ('.');
	if (!name.substring (0, index + 1).equals (PACKAGE_PREFIX)) {
		SWT.error (SWT.ERROR_INVALID_SUBCLASS);
	}
}
/**
 * Sets the selection in the receiver's text field to an empty
 * selection starting just before the first character. If the
 * text field is editable, this has the effect of placing the
 * i-beam at the start of the text.
 * <p>
 * Note: To clear the selected items in the receiver's list,
 * use <code>deselectAll()</code>.
 * </p>
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @see #deselectAll
 */
public void clearSelection () {
	checkWidget ();
	text.clearSelection ();
	list.deselectAll ();
}
void comboEvent (Event event) {
	switch (event.type) {
		case SWT.Dispose:
			removeListener(SWT.Dispose, listener);
			notifyListeners(SWT.Dispose, event);
			event.type = SWT.None;

			if (popup != null && !popup.isDisposed ()) {
				list.removeListener (SWT.Dispose, listener);
				popup.dispose ();
			}
			Shell shell = getShell ();
			shell.removeListener (SWT.Deactivate, listener);
			Display display = getDisplay ();
			display.removeFilter (SWT.FocusIn, filter);
			popup = null;
			text = null;
			list = null;
			arrow = null;
			_shell = null;
			break;
		case SWT.FocusIn:
			Control focusControl = getDisplay ().getFocusControl ();
			if (focusControl == arrow || focusControl == list) return;
			if (isDropped()) {
				list.setFocus();
			} else {
				text.setFocus();
			}
			break;
		case SWT.FocusOut:
			text.clearSelection();
			break;
		case SWT.Move:
			dropDown (false);
			break;
		case SWT.Resize:
			internalLayout (false);
			break;
	}
}

@Override
public Point computeSize (int wHint, int hHint, boolean changed) {
	checkWidget ();
	int width = 0, height = 0;
	GC gc = new GC (text);
	int spacer = gc.stringExtent (" ").x; //$NON-NLS-1$
	int textWidth = gc.stringExtent (text.getText ()).x;
	for (String item : list.getItems ()) {
		textWidth = Math.max (gc.stringExtent (item).x, textWidth);
	}
	gc.dispose ();
	Point textSize = text.computeSize (SWT.DEFAULT, SWT.DEFAULT, changed);
	Point arrowSize = arrow.computeSize (SWT.DEFAULT, SWT.DEFAULT, changed);
	Point listSize = list.computeSize (SWT.DEFAULT, SWT.DEFAULT, changed);
	int borderWidth = getBorderWidth ();

	height = Math.max (textSize.y, arrowSize.y);
	width = Math.max (textWidth + 2*spacer + arrowSize.x + 2*borderWidth, listSize.x);
	if (wHint != SWT.DEFAULT) width = wHint;
	if (hHint != SWT.DEFAULT) height = hHint;
	return new Point (width + 2*borderWidth, height + 2*borderWidth);
}
/**
 * Copies the selected text.
 * <p>
 * The current selection is copied to the clipboard.
 * </p>
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @since 3.3
 */
public void copy () {
	checkWidget ();
	text.copy ();
}
void createPopup(String[] items, int selectionIndex) {
	// create shell and list
	popup = new Shell (getShell (), SWT.NO_TRIM | SWT.ON_TOP);
	int style = getStyle ();
	int listStyle = SWT.SINGLE | SWT.V_SCROLL | SWT.H_SCROLL;
	if ((style & SWT.FLAT) != 0) listStyle |= SWT.FLAT;
	if ((style & SWT.RIGHT_TO_LEFT) != 0) listStyle |= SWT.RIGHT_TO_LEFT;
	if ((style & SWT.LEFT_TO_RIGHT) != 0) listStyle |= SWT.LEFT_TO_RIGHT;
	list = new List (popup, listStyle);
	if (font != null) list.setFont (font);
	if (foreground != null) list.setForeground (foreground);
	if (background != null) list.setBackground (background);

	int [] popupEvents = {SWT.Close, SWT.Paint};
	for (int popupEvent : popupEvents)
		popup.addListener (popupEvent, listener);
	int [] listEvents = {SWT.MouseUp, SWT.Selection, SWT.Traverse, SWT.KeyDown, SWT.KeyUp, SWT.FocusIn, SWT.FocusOut, SWT.Dispose};
	for (int listEvent : listEvents)
		list.addListener (listEvent, listener);

	if (items != null) list.setItems (items);
	if (selectionIndex != -1) list.setSelection (selectionIndex);
}
/**
 * Cuts the selected text.
 * <p>
 * The current selection is first copied to the
 * clipboard and then deleted from the widget.
 * </p>
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @since 3.3
 */
public void cut () {
	checkWidget ();
	text.cut ();
}
/**
 * Deselects the item at the given zero-relative index in the receiver's
 * list.  If the item at the index was already deselected, it remains
 * deselected. Indices that are out of range are ignored.
 *
 * @param index the index of the item to deselect
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void deselect (int index) {
	checkWidget ();
	if (0 <= index && index < list.getItemCount () &&
			index == list.getSelectionIndex() &&
			text.getText().equals(list.getItem(index))) {
		text.setText("");  //$NON-NLS-1$
		list.deselect (index);
	}
}
/**
 * Deselects all selected items in the receiver's list.
 * <p>
 * Note: To clear the selection in the receiver's text field,
 * use <code>clearSelection()</code>.
 * </p>
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @see #clearSelection
 */
public void deselectAll () {
	checkWidget ();
	text.setText("");  //$NON-NLS-1$
	list.deselectAll ();
}
void dropDown (boolean drop) {
	if (drop == isDropped ()) return;
	Display display = getDisplay ();
	if (!drop) {
		display.removeFilter (SWT.Selection, filter);
		popup.setVisible (false);
		if (!isDisposed () && isFocusControl()) {
			text.setFocus();
		}
		return;
	}
	if (!isVisible()) return;
	if (getShell() != popup.getParent ()) {
		String[] items = list.getItems ();
		int selectionIndex = list.getSelectionIndex ();
		list.removeListener (SWT.Dispose, listener);
		popup.dispose();
		popup = null;
		list = null;
		createPopup (items, selectionIndex);
	}

	Point comboSize = getSize ();
	int itemCount = list.getItemCount ();
	itemCount = (itemCount == 0) ? visibleItemCount : Math.min(visibleItemCount, itemCount);
	int itemHeight = list.getItemHeight () * itemCount;
	Point listSize = list.computeSize (SWT.DEFAULT, itemHeight, false);
	Rectangle displayRect = getMonitor ().getClientArea ();
	list.setBounds (1, 1, Math.max (comboSize.x - 2, Math.min(listSize.x, displayRect.width - 2)), listSize.y);

	int index = list.getSelectionIndex ();
	if (index != -1) list.setTopIndex (index);
	Rectangle listRect = list.getBounds ();
	Rectangle parentRect = display.map (getParent (), null, getBounds ());
	int width = listRect.width + 2;
	int height = listRect.height + 2;
	int x = parentRect.x;
	if (x + width > displayRect.x + displayRect.width) {
		x = displayRect.x + displayRect.width - width;
	}
	int y = parentRect.y + comboSize.y;
	if (y + height > displayRect.y + displayRect.height) {
		int popUpwardsHeight = (parentRect.y - height < displayRect.y) ? parentRect.y - displayRect.y : height;
		int popDownwardsHeight = displayRect.y + displayRect.height - y;
		if (popUpwardsHeight > popDownwardsHeight) {
			height = popUpwardsHeight;
			y = parentRect.y - popUpwardsHeight;
		} else {
			height = popDownwardsHeight;
		}
		listRect.height = height - 2;
	}
	/*
	 * Invisible HScrollBar lead to empty space at end of CCombo drop-down.
	 * Fix is to reduce height of list and shell in that case, bug 388126.
	 */
	ScrollBar hBar = list.getHorizontalBar();
	int emptyHBarSpace = hBar.isVisible () ? 0 : hBar.getSize ().y;
	list.setSize (listRect.width, listRect.height - emptyHBarSpace);
	popup.setBounds (x, y, width, height - emptyHBarSpace);
	popup.setVisible (true);
	if (isFocusControl()) list.setFocus ();

	/*
	 * Add a filter to listen to scrolling of the parent composite, when the
	 * drop-down is visible. Remove the filter when drop-down is not
	 * visible.
	 */
	display.removeFilter (SWT.Selection, filter);
	display.addFilter (SWT.Selection, filter);
}
/*
 * Return the lowercase of the first non-'&' character following
 * an '&' character in the given string. If there are no '&'
 * characters in the given string, return '\0'.
 */
char _findMnemonic (String string) {
	if (string == null) return '\0';
	int index = 0;
	int length = string.length ();
	do {
		while (index < length && string.charAt (index) != '&') index++;
		if (++index >= length) return '\0';
		if (string.charAt (index) != '&') return Character.toLowerCase (string.charAt (index));
		index++;
	} while (index < length);
	return '\0';
}
/*
 * Return the Label immediately preceding the receiver in the z-order,
 * or null if none.
 */
String getAssociatedLabel () {
	Control[] siblings = getParent ().getChildren ();
	for (int i = 0; i < siblings.length; i++) {
		if (siblings [i] == this) {
			if (i > 0) {
				Control sibling = siblings [i-1];
				if (sibling instanceof Label) return ((Label) sibling).getText();
				if (sibling instanceof CLabel) return ((CLabel) sibling).getText();
			}
			break;
		}
	}
	return null;
}
/**
 * Returns the horizontal alignment.
 * The alignment style (LEFT, CENTER or RIGHT) is returned.
 *
 * @return SWT.LEFT, SWT.RIGHT or SWT.CENTER
 * @since 3.113
 */
public int getAlignment() {
	return text.getStyle() & (SWT.LEFT | SWT.CENTER | SWT.RIGHT);
}
@Override
public Control [] getChildren () {
	checkWidget();
	return new Control [0];
}
/**
 * Gets the editable state.
 *
 * @return whether or not the receiver is editable
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @since 3.0
 */
public boolean getEditable () {
	checkWidget ();
	return text.getEditable();
}
/**
 * Returns the item at the given, zero-relative index in the
 * receiver's list. Throws an exception if the index is out
 * of range.
 *
 * @param index the index of the item to return
 * @return the item at the given index
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_RANGE - if the index is not between 0 and the number of elements in the list minus 1 (inclusive)</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public String getItem (int index) {
	checkWidget();
	return list.getItem (index);
}
/**
 * Returns the number of items contained in the receiver's list.
 *
 * @return the number of items
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public int getItemCount () {
	checkWidget ();
	return list.getItemCount ();
}
/**
 * Returns the height of the area which would be used to
 * display <em>one</em> of the items in the receiver's list.
 *
 * @return the height of one item
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public int getItemHeight () {
	checkWidget ();
	return list.getItemHeight ();
}
/**
 * Returns an array of <code>String</code>s which are the items
 * in the receiver's list.
 * <p>
 * Note: This is not the actual structure used by the receiver
 * to maintain its list of items, so modifying the array will
 * not affect the receiver.
 * </p>
 *
 * @return the items in the receiver's list
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public String [] getItems () {
	checkWidget ();
	return list.getItems ();
}
/**
 * Returns <code>true</code> if the receiver's list is visible,
 * and <code>false</code> otherwise.
 * <p>
 * If one of the receiver's ancestors is not visible or some
 * other condition makes the receiver not visible, this method
 * may still indicate that it is considered visible even though
 * it may not actually be showing.
 * </p>
 *
 * @return the receiver's list's visibility state
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @since 3.4
 */
public boolean getListVisible () {
	checkWidget ();
	return isDropped();
}
@Override
public Menu getMenu() {
	return text.getMenu();
}
/**
 * Returns a <code>Point</code> whose x coordinate is the start
 * of the selection in the receiver's text field, and whose y
 * coordinate is the end of the selection. The returned values
 * are zero-relative. An "empty" selection as indicated by
 * the the x and y coordinates having the same value.
 *
 * @return a point representing the selection start and end
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public Point getSelection () {
	checkWidget ();
	return text.getSelection ();
}
/**
 * Returns the zero-relative index of the item which is currently
 * selected in the receiver's list, or -1 if no item is selected.
 *
 * @return the index of the selected item
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public int getSelectionIndex () {
	checkWidget ();
	return list.getSelectionIndex ();
}
@Override
public Shell getShell () {
	checkWidget ();
	Shell shell = super.getShell ();
	if (shell != _shell) {
		if (_shell != null && !_shell.isDisposed ()) {
			_shell.removeListener (SWT.Deactivate, listener);
		}
		_shell = shell;
	}
	return _shell;
}
@Override
public int getStyle () {
	int style = super.getStyle ();
	style &= ~SWT.READ_ONLY;
	if (!text.getEditable()) style |= SWT.READ_ONLY;
	style &= ~(SWT.LEFT | SWT.CENTER | SWT.RIGHT);
	style |= getAlignment();
	return style;
}
/**
 * Returns a string containing a copy of the contents of the
 * receiver's text field.
 *
 * @return the receiver's text
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public String getText () {
	checkWidget ();
	return text.getText ();
}
/**
 * Returns the height of the receivers's text field.
 *
 * @return the text height
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public int getTextHeight () {
	checkWidget ();
	return text.getLineHeight ();
}
/**
 * Returns the maximum number of characters that the receiver's
 * text field is capable of holding. If this has not been changed
 * by <code>setTextLimit()</code>, it will be the constant
 * <code>Combo.LIMIT</code>.
 *
 * @return the text limit
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public int getTextLimit () {
	checkWidget ();
	return text.getTextLimit ();
}
/**
 * Gets the number of items that are visible in the drop
 * down portion of the receiver's list.
 *
 * @return the number of items that are visible
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @since 3.0
 */
public int getVisibleItemCount () {
	checkWidget ();
	return visibleItemCount;
}
void handleFocus (int type) {
	switch (type) {
		case SWT.FocusIn: {
			if (hasFocus) return;
			if (getEditable ()) text.selectAll ();
			hasFocus = true;
			Shell shell = getShell ();
			shell.removeListener (SWT.Deactivate, listener);
			shell.addListener (SWT.Deactivate, listener);
			Display display = getDisplay ();
			display.removeFilter (SWT.FocusIn, filter);
			display.addFilter (SWT.FocusIn, filter);
			Event e = new Event ();
			notifyListeners (SWT.FocusIn, e);
			break;
		}
		case SWT.FocusOut: {
			if (!hasFocus) return;
			Control focusControl = getDisplay ().getFocusControl ();
			if (focusControl == arrow || focusControl == list || focusControl == text) return;
			hasFocus = false;
			Shell shell = getShell ();
			shell.removeListener(SWT.Deactivate, listener);
			Display display = getDisplay ();
			display.removeFilter (SWT.FocusIn, filter);
			Event e = new Event ();
			notifyListeners (SWT.FocusOut, e);
			break;
		}
	}
}
void handleScroll(Event event) {
	ScrollBar scrollBar = (ScrollBar)event.widget;
	Control scrollableParent = scrollBar.getParent();
	if (scrollableParent.equals(list)) return;
	if (isParentScrolling(scrollableParent)) dropDown(false);
}
/**
 * Searches the receiver's list starting at the first item
 * (index 0) until an item is found that is equal to the
 * argument, and returns the index of that item. If no item
 * is found, returns -1.
 *
 * @param string the search item
 * @return the index of the item
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the string is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public int indexOf (String string) {
	checkWidget ();
	if (string == null) SWT.error (SWT.ERROR_NULL_ARGUMENT);
	return list.indexOf (string);
}
/**
 * Searches the receiver's list starting at the given,
 * zero-relative index until an item is found that is equal
 * to the argument, and returns the index of that item. If
 * no item is found or the starting index is out of range,
 * returns -1.
 *
 * @param string the search item
 * @param start the zero-relative index at which to begin the search
 * @return the index of the item
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the string is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public int indexOf (String string, int start) {
	checkWidget ();
	if (string == null) SWT.error (SWT.ERROR_NULL_ARGUMENT);
	return list.indexOf (string, start);
}

void initAccessible() {
	AccessibleAdapter accessibleAdapter = new AccessibleAdapter () {
		@Override
		public void getName (AccessibleEvent e) {
			String name = null;
			String text = getAssociatedLabel ();
			if (text != null) {
				name = stripMnemonic (text);
			}
			e.result = name;
		}
		@Override
		public void getKeyboardShortcut(AccessibleEvent e) {
			String shortcut = null;
			String text = getAssociatedLabel ();
			if (text != null) {
				char mnemonic = _findMnemonic (text);
				if (mnemonic != '\0') {
					shortcut = "Alt+"+mnemonic; //$NON-NLS-1$
				}
			}
			e.result = shortcut;
		}
		@Override
		public void getHelp (AccessibleEvent e) {
			e.result = getToolTipText ();
		}
	};
	getAccessible ().addAccessibleListener (accessibleAdapter);
	text.getAccessible ().addAccessibleListener (accessibleAdapter);
	list.getAccessible ().addAccessibleListener (accessibleAdapter);

	arrow.getAccessible ().addAccessibleListener (new AccessibleAdapter() {
		@Override
		public void getName (AccessibleEvent e) {
			e.result = isDropped () ? SWT.getMessage ("SWT_Close") : SWT.getMessage ("SWT_Open"); //$NON-NLS-1$ //$NON-NLS-2$
		}
		@Override
		public void getKeyboardShortcut (AccessibleEvent e) {
			e.result = "Alt+Down Arrow"; //$NON-NLS-1$
		}
		@Override
		public void getHelp (AccessibleEvent e) {
			e.result = getToolTipText ();
		}
	});

	getAccessible().addAccessibleTextListener (new AccessibleTextAdapter() {
		@Override
		public void getCaretOffset (AccessibleTextEvent e) {
			e.offset = text.getCaretPosition ();
		}
		@Override
		public void getSelectionRange(AccessibleTextEvent e) {
			Point sel = text.getSelection();
			e.offset = sel.x;
			e.length = sel.y - sel.x;
		}
	});

	getAccessible().addAccessibleControlListener (new AccessibleControlAdapter() {
		@Override
		public void getChildAtPoint (AccessibleControlEvent e) {
			Point testPoint = toControl (e.x, e.y);
			if (getBounds ().contains (testPoint)) {
				e.childID = ACC.CHILDID_SELF;
			}
		}

		@Override
		public void getLocation (AccessibleControlEvent e) {
			Rectangle location = getBounds ();
			Point pt = getParent().toDisplay (location.x, location.y);
			e.x = pt.x;
			e.y = pt.y;
			e.width = location.width;
			e.height = location.height;
		}

		@Override
		public void getChildCount (AccessibleControlEvent e) {
			e.detail = 0;
		}

		@Override
		public void getRole (AccessibleControlEvent e) {
			e.detail = ACC.ROLE_COMBOBOX;
		}

		@Override
		public void getState (AccessibleControlEvent e) {
			e.detail = ACC.STATE_NORMAL;
		}

		@Override
		public void getValue (AccessibleControlEvent e) {
			e.result = getText ();
		}
	});

	text.getAccessible ().addAccessibleControlListener (new AccessibleControlAdapter () {
		@Override
		public void getRole (AccessibleControlEvent e) {
			e.detail = text.getEditable () ? ACC.ROLE_TEXT : ACC.ROLE_LABEL;
		}
	});

	arrow.getAccessible ().addAccessibleControlListener (new AccessibleControlAdapter() {
		@Override
		public void getDefaultAction (AccessibleControlEvent e) {
			e.result = isDropped () ? SWT.getMessage ("SWT_Close") : SWT.getMessage ("SWT_Open"); //$NON-NLS-1$ //$NON-NLS-2$
		}
	});
}
boolean isDropped () {
	return !isDisposed() && popup.getVisible ();
}
@Override
public boolean isFocusControl () {
	checkWidget();
	Predicate<Control> checkFocusControl = control -> (control != null && !control.isDisposed() && control.isFocusControl ());
	if (checkFocusControl.test(text) || checkFocusControl.test(arrow) ||
			checkFocusControl.test(list) || checkFocusControl.test(popup)) {
		return true;
	}
	return super.isFocusControl ();
}

boolean isParentScrolling(Control scrollableParent) {
	Control parent = this.getParent();
	while (parent != null) {
		if (parent.equals(scrollableParent))
			return true;
		parent = parent.getParent();
	}
	return false;
}
void internalLayout (boolean changed) {
	if (isDropped ()) dropDown (false);
	Rectangle rect = getClientArea ();
	int width = rect.width;
	int height = rect.height;
	Point arrowSize = arrow.computeSize (SWT.DEFAULT, height, changed);
	text.setBounds (0, 0, width - arrowSize.x, height);
	arrow.setBounds (width - arrowSize.x, 0, arrowSize.x, arrowSize.y);
}
void listEvent (Event event) {
	switch (event.type) {
		case SWT.Dispose:
			if (getShell () != popup.getParent ()) {
				String[] items = list.getItems ();
				int selectionIndex = list.getSelectionIndex ();
				popup = null;
				list = null;
				createPopup (items, selectionIndex);
			}
			break;
		case SWT.FocusIn: {
			handleFocus (SWT.FocusIn);
			break;
		}
		case SWT.FocusOut: {
			/*
			 * Behavior in Windows, GTK & Cocoa: When the arrow button is pressed
			 * with the popup list visible, the following events are received-
			 * popup control receives a deactivate event,
			 * list receives focus lost event, and then
			 * arrow button receives a selection event.
			 * If we hide the popup in the focus out event, the selection event will
			 * show it again. To prevent the popup from showing again, we will detect
			 * this case and let the selection event of the arrow button hide the popup.
			 */
			Point point = arrow.toControl(getDisplay().getCursorLocation());
			Point size = arrow.getSize();
			Rectangle rect = new Rectangle(0, 0, size.x, size.y);
			if (rect.contains(point)) {
				boolean comboShellActivated = getDisplay ().getActiveShell () == getShell ();
				if (!comboShellActivated) dropDown (false);
				break;
			}
			dropDown (false);
			break;
		}
		case SWT.MouseUp: {
			if (event.button != 1) return;
			dropDown (false);
			break;
		}
		case SWT.Selection: {
			int index = list.getSelectionIndex ();
			if (index == -1) return;
			text.setText (list.getItem (index));
			if (text.getEditable() && text.isFocusControl()) text.selectAll ();
			list.setSelection (index);
			Event e = new Event ();
			e.time = event.time;
			e.stateMask = event.stateMask;
			e.doit = event.doit;
			notifyListeners (SWT.Selection, e);
			event.doit = e.doit;
			break;
		}
		case SWT.Traverse: {
			switch (event.detail) {
				case SWT.TRAVERSE_RETURN:
				case SWT.TRAVERSE_ESCAPE:
				case SWT.TRAVERSE_ARROW_PREVIOUS:
				case SWT.TRAVERSE_ARROW_NEXT:
					event.doit = false;
					break;
				case SWT.TRAVERSE_TAB_NEXT:
				case SWT.TRAVERSE_TAB_PREVIOUS:
					event.doit = text.traverse(event.detail);
					event.detail = SWT.TRAVERSE_NONE;
					if (event.doit) dropDown(false);
					return;
			}
			Event e = new Event ();
			e.time = event.time;
			e.detail = event.detail;
			e.doit = event.doit;
			e.character = event.character;
			e.keyCode = event.keyCode;
			e.keyLocation = event.keyLocation;
			notifyListeners (SWT.Traverse, e);
			event.doit = e.doit;
			event.detail = e.detail;
			break;
		}
		case SWT.KeyUp: {
			Event e = new Event ();
			e.time = event.time;
			e.character = event.character;
			e.keyCode = event.keyCode;
			e.keyLocation = event.keyLocation;
			e.stateMask = event.stateMask;
			notifyListeners (SWT.KeyUp, e);
			event.doit = e.doit;
			break;
		}
		case SWT.KeyDown: {
			if (event.character == SWT.ESC) {
				// Escape key cancels popup list
				dropDown (false);
			}
			if ((event.stateMask & SWT.ALT) != 0 && (event.keyCode == SWT.ARROW_UP || event.keyCode == SWT.ARROW_DOWN)) {
				dropDown (false);
			}
			if (event.character == SWT.CR) {
				// Enter causes default selection
				dropDown (false);
				Event e = new Event ();
				e.time = event.time;
				e.stateMask = event.stateMask;
				notifyListeners (SWT.DefaultSelection, e);
			}
			// At this point the widget may have been disposed.
			// If so, do not continue.
			if (isDisposed ()) break;
			Event e = new Event();
			e.time = event.time;
			e.character = event.character;
			e.keyCode = event.keyCode;
			e.keyLocation = event.keyLocation;
			e.stateMask = event.stateMask;
			notifyListeners(SWT.KeyDown, e);
			event.doit = e.doit;
			break;

		}
	}
}
/**
 * Pastes text from clipboard.
 * <p>
 * The selected text is deleted from the widget
 * and new text inserted from the clipboard.
 * </p>
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @since 3.3
 */
public void paste () {
	checkWidget ();
	text.paste ();
}
void popupEvent(Event event) {
	switch (event.type) {
		case SWT.Paint:
			// draw black rectangle around list
			Rectangle listRect = list.getBounds();
			Color black = getDisplay().getSystemColor(SWT.COLOR_BLACK);
			event.gc.setForeground(black);
			event.gc.drawRectangle(0, 0, listRect.width + 1, listRect.height + 1);
			break;
		case SWT.Close:
			event.doit = false;
			dropDown (false);
			break;
	}
}
@Override
public void redraw () {
	super.redraw();
	text.redraw();
	arrow.redraw();
	if (popup.isVisible()) list.redraw();
}
@Override
public void redraw (int x, int y, int width, int height, boolean all) {
	super.redraw(x, y, width, height, true);
}

/**
 * Removes the item from the receiver's list at the given
 * zero-relative index.
 *
 * @param index the index for the item
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_RANGE - if the index is not between 0 and the number of elements in the list minus 1 (inclusive)</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void remove (int index) {
	checkWidget();
	list.remove (index);
}
/**
 * Removes the items from the receiver's list which are
 * between the given zero-relative start and end
 * indices (inclusive).
 *
 * @param start the start of the range
 * @param end the end of the range
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_RANGE - if either the start or end are not between 0 and the number of elements in the list minus 1 (inclusive)</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void remove (int start, int end) {
	checkWidget();
	list.remove (start, end);
}
/**
 * Searches the receiver's list starting at the first item
 * until an item is found that is equal to the argument,
 * and removes that item from the list.
 *
 * @param string the item to remove
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the string is null</li>
 *    <li>ERROR_INVALID_ARGUMENT - if the string is not found in the list</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void remove (String string) {
	checkWidget();
	if (string == null) SWT.error (SWT.ERROR_NULL_ARGUMENT);
	list.remove (string);
}
/**
 * Removes all of the items from the receiver's list and clear the
 * contents of receiver's text field.
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void removeAll () {
	checkWidget();
	text.setText (""); //$NON-NLS-1$
	list.removeAll ();
}
/**
 * Removes the listener from the collection of listeners who will
 * be notified when the receiver's text is modified.
 *
 * @param listener the listener which should no longer be notified
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @see ModifyListener
 * @see #addModifyListener
 */
public void removeModifyListener (ModifyListener listener) {
	checkWidget();
	if (listener == null) SWT.error (SWT.ERROR_NULL_ARGUMENT);
	removeTypedListener(SWT.Modify, listener);
}
/**
 * Removes the listener from the collection of listeners who will
 * be notified when the user changes the receiver's selection.
 *
 * @param listener the listener which should no longer be notified
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @see SelectionListener
 * @see #addSelectionListener
 */
public void removeSelectionListener (SelectionListener listener) {
	checkWidget();
	if (listener == null) SWT.error (SWT.ERROR_NULL_ARGUMENT);
	removeTypedListener(SWT.Selection, listener);
	removeTypedListener(SWT.DefaultSelection, listener);
}
/**
 * Removes the listener from the collection of listeners who will
 * be notified when the control is verified.
 *
 * @param listener the listener which should no longer be notified
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @see VerifyListener
 * @see #addVerifyListener
 *
 * @since 3.3
 */
public void removeVerifyListener (VerifyListener listener) {
	checkWidget();
	if (listener == null) SWT.error (SWT.ERROR_NULL_ARGUMENT);
	removeTypedListener(SWT.Verify, listener);
}
/**
 * Selects the item at the given zero-relative index in the receiver's
 * list.  If the item at the index was already selected, it remains
 * selected. Indices that are out of range are ignored.
 *
 * @param index the index of the item to select
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void select (int index) {
	checkWidget();
	if (index == -1) {
		list.deselectAll ();
		text.setText (""); //$NON-NLS-1$
		return;
	}
	if (0 <= index && index < list.getItemCount()) {
		if (index != getSelectionIndex()) {
			text.setText (list.getItem (index));
			if (text.getEditable() && text.isFocusControl()) text.selectAll ();
			list.select (index);
			list.showSelection ();
		}
	}
}

/**
 * Set the horizontal alignment of the CCombo.
 * Use the values LEFT, CENTER and RIGHT to align image and text within the available space.
 *
 * @param align the alignment style of LEFT, RIGHT or CENTER
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 *    <li>ERROR_INVALID_ARGUMENT - if the value of align is not one of SWT.LEFT, SWT.RIGHT or SWT.CENTER</li>
 * </ul>
 * @since 3.113
 */
public void setAlignment(int align) {
	checkWidget();
	int styleWithoutAlign = getStyle() & ~(SWT.LEFT | SWT.CENTER | SWT.RIGHT);
	createText(styleWithoutAlign | align);
}
@Override
public void setBackground (Color color) {
	super.setBackground(color);
	background = color;
	if (text != null) text.setBackground(color);
	if (list != null) list.setBackground(color);
	if (arrow != null) arrow.setBackground(color);
}
/**
 * Sets the editable state.
 *
 * @param editable the new editable state
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @since 3.0
 */
public void setEditable (boolean editable) {
	checkWidget ();
	text.setEditable(editable);
}
@Override
public void setEnabled (boolean enabled) {
	super.setEnabled(enabled);
	if (popup != null) popup.setVisible (false);
	if (text != null) text.setEnabled(enabled);
	if (arrow != null) arrow.setEnabled(enabled);
}
@Override
public boolean setFocus () {
	checkWidget();
	if (!isEnabled () || !getVisible ()) return false;
	if (isFocusControl ()) return true;
	return text.setFocus ();
}
@Override
public void setFont (Font font) {
	super.setFont (font);
	this.font = font;
	text.setFont (font);
	list.setFont (font);
	internalLayout (true);
}
@Override
public void setForeground (Color color) {
	super.setForeground(color);
	foreground = color;
	if (text != null) text.setForeground(color);
	if (list != null) list.setForeground(color);
	if (arrow != null) arrow.setForeground(color);
}
/**
 * Sets the text of the item in the receiver's list at the given
 * zero-relative index to the string argument. This is equivalent
 * to <code>remove</code>'ing the old item at the index, and then
 * <code>add</code>'ing the new item at that index.
 *
 * @param index the index for the item
 * @param string the new text for the item
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_RANGE - if the index is not between 0 and the number of elements in the list minus 1 (inclusive)</li>
 *    <li>ERROR_NULL_ARGUMENT - if the string is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void setItem (int index, String string) {
	checkWidget();
	list.setItem (index, string);
}
/**
 * Sets the receiver's list to be the given array of items.
 *
 * @param items the array of items
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the items array is null</li>
 *    <li>ERROR_INVALID_ARGUMENT - if an item in the items array is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void setItems (String [] items) {
	checkWidget ();
	list.setItems (items);
	if (!text.getEditable ()) text.setText (""); //$NON-NLS-1$
}
/**
 * Sets the layout which is associated with the receiver to be
 * the argument which may be null.
 * <p>
 * Note: No Layout can be set on this Control because it already
 * manages the size and position of its children.
 * </p>
 *
 * @param layout the receiver's new layout or null
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
@Override
public void setLayout (Layout layout) {
	checkWidget ();
	return;
}
/**
 * Marks the receiver's list as visible if the argument is <code>true</code>,
 * and marks it invisible otherwise.
 * <p>
 * If one of the receiver's ancestors is not visible or some
 * other condition makes the receiver not visible, marking
 * it visible may not actually cause it to be displayed.
 * </p>
 *
 * @param visible the new visibility state
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @since 3.4
 */
public void setListVisible (boolean visible) {
	checkWidget ();
	dropDown(visible);
}
@Override
public void setMenu(Menu menu) {
	text.setMenu(menu);
}
/**
 * Sets the selection in the receiver's text field to the
 * range specified by the argument whose x coordinate is the
 * start of the selection and whose y coordinate is the end
 * of the selection.
 *
 * @param selection a point representing the new selection start and end
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the point is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void setSelection (Point selection) {
	checkWidget();
	if (selection == null) SWT.error (SWT.ERROR_NULL_ARGUMENT);
	text.setSelection (selection.x, selection.y);
}

/**
 * Sets the contents of the receiver's text field to the
 * given string.
 * <p>
 * Note: The text field in a <code>Combo</code> is typically
 * only capable of displaying a single line of text. Thus,
 * setting the text to a string containing line breaks or
 * other special characters will probably cause it to
 * display incorrectly.
 * </p><p>
 * Also note, if control characters like '\n', '\t' etc. are used
 * in the string, then the behavior is platform dependent.
 * </p>
 *
 * @param string the new text
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the string is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void setText (String string) {
	checkWidget();
	if (string == null) SWT.error (SWT.ERROR_NULL_ARGUMENT);
	int index = list.indexOf (string);
	if (index == -1) {
		list.deselectAll ();
		text.setText (string);
		return;
	}
	text.setText (string);
	if (text.getEditable() && text.isFocusControl()) text.selectAll ();
	list.setSelection (index);
	list.showSelection ();
}
/**
 * Sets the maximum number of characters that the receiver's
 * text field is capable of holding to be the argument.
 *
 * @param limit new text limit
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_CANNOT_BE_ZERO - if the limit is zero</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void setTextLimit (int limit) {
	checkWidget();
	text.setTextLimit (limit);
}

@Override
public void setToolTipText (String string) {
	checkWidget();
	super.setToolTipText(string);
	arrow.setToolTipText (string);
	text.setToolTipText (string);
}

@Override
public void setVisible (boolean visible) {
	super.setVisible(visible);
	/*
	 * At this point the widget may have been disposed in a FocusOut event.
	 * If so then do not continue.
	 */
	if (isDisposed ()) return;
	// TEMPORARY CODE
	if (popup == null || popup.isDisposed ()) return;
	if (!visible) popup.setVisible (false);
}
/**
 * Sets the number of items that are visible in the drop
 * down portion of the receiver's list.
 *
 * @param count the new number of items to be visible
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @since 3.0
 */
public void setVisibleItemCount (int count) {
	checkWidget ();
	if (count < 0) return;
	visibleItemCount = count;
}
String stripMnemonic (String string) {
	int index = 0;
	int length = string.length ();
	do {
		while ((index < length) && (string.charAt (index) != '&')) index++;
		if (++index >= length) return string;
		if (string.charAt (index) != '&') {
			return string.substring(0, index-1) + string.substring(index, length);
		}
		index++;
	} while (index < length);
	return string;
}
void textEvent (Event event) {
	switch (event.type) {
		case SWT.FocusIn: {
			handleFocus (SWT.FocusIn);
			break;
		}
		case SWT.DefaultSelection: {
			dropDown (false);
			Event e = new Event ();
			e.time = event.time;
			e.stateMask = event.stateMask;
			notifyListeners (SWT.DefaultSelection, e);
			break;
		}
		case SWT.DragDetect:
		case SWT.MouseDoubleClick:
		case SWT.MouseMove:
		case SWT.MouseEnter:
		case SWT.MouseExit:
		case SWT.MouseHover: {
			Point pt = getDisplay ().map (text, this, event.x, event.y);
			event.x = pt.x; event.y = pt.y;
			notifyListeners (event.type, event);
			event.type = SWT.None;
			break;
		}
		case SWT.KeyDown: {
			Event keyEvent = new Event ();
			keyEvent.time = event.time;
			keyEvent.character = event.character;
			keyEvent.keyCode = event.keyCode;
			keyEvent.keyLocation = event.keyLocation;
			keyEvent.stateMask = event.stateMask;
			notifyListeners (SWT.KeyDown, keyEvent);
			if (isDisposed ()) break;
			event.doit = keyEvent.doit;
			if (!event.doit) break;
			if (event.keyCode == SWT.ARROW_UP || event.keyCode == SWT.ARROW_DOWN) {
				event.doit = false;
				if ((event.stateMask & SWT.ALT) != 0) {
					boolean dropped = isDropped ();
					if (text.getEditable() && text.isFocusControl()) text.selectAll ();
					if (!dropped) setFocus ();
					dropDown (!dropped);
					break;
				}

				int oldIndex = getSelectionIndex ();
				if (event.keyCode == SWT.ARROW_UP) {
					select (Math.max (oldIndex - 1, 0));
				} else {
					select (Math.min (oldIndex + 1, getItemCount () - 1));
				}
				if (oldIndex != getSelectionIndex ()) {
					Event e = new Event();
					e.time = event.time;
					e.stateMask = event.stateMask;
					notifyListeners (SWT.Selection, e);
				}
				if (isDisposed ()) break;
			}

			// Further work : Need to add support for incremental search in
			// pop up list as characters typed in text widget
			break;
		}
		case SWT.KeyUp: {
			Event e = new Event ();
			e.time = event.time;
			e.character = event.character;
			e.keyCode = event.keyCode;
			e.keyLocation = event.keyLocation;
			e.stateMask = event.stateMask;
			notifyListeners (SWT.KeyUp, e);
			event.doit = e.doit;
			break;
		}
		case SWT.MenuDetect: {
			Event e = new Event ();
			e.time = event.time;
			e.detail = event.detail;
			e.x = event.x;
			e.y = event.y;
			if (event.detail == SWT.MENU_KEYBOARD) {
				Point pt = getDisplay().map(text, null, text.getCaretLocation());
				e.x = pt.x;
				e.y = pt.y;
			}
			notifyListeners (SWT.MenuDetect, e);
			event.doit = e.doit;
			event.x = e.x;
			event.y = e.y;
			break;
		}
		case SWT.Modify: {
			list.deselectAll ();
			Event e = new Event ();
			e.time = event.time;
			notifyListeners (SWT.Modify, e);
			break;
		}
		case SWT.MouseDown: {
			Point pt = getDisplay ().map (text, this, event.x, event.y);
			Event mouseEvent = new Event ();
			mouseEvent.button = event.button;
			mouseEvent.count = event.count;
			mouseEvent.stateMask = event.stateMask;
			mouseEvent.time = event.time;
			mouseEvent.x = pt.x; mouseEvent.y = pt.y;
			notifyListeners (SWT.MouseDown, mouseEvent);
			if (isDisposed ()) break;
			event.doit = mouseEvent.doit;
			if (!event.doit) break;
			if (event.button != 1) return;
			if (text.getEditable ()) return;
			boolean dropped = isDropped ();
			if (text.getEditable() && text.isFocusControl()) text.selectAll ();
			if (!dropped) setFocus ();
			dropDown (!dropped);
			break;
		}
		case SWT.MouseUp: {
			Point pt = getDisplay ().map (text, this, event.x, event.y);
			Event mouseEvent = new Event ();
			mouseEvent.button = event.button;
			mouseEvent.count = event.count;
			mouseEvent.stateMask = event.stateMask;
			mouseEvent.time = event.time;
			mouseEvent.x = pt.x; mouseEvent.y = pt.y;
			notifyListeners (SWT.MouseUp, mouseEvent);
			if (isDisposed ()) break;
			event.doit = mouseEvent.doit;
			if (!event.doit) break;
			if (event.button != 1) return;
			if (text.getEditable ()) return;
			if (text.getEditable() && text.isFocusControl()) text.selectAll ();
			break;
		}
		case SWT.MouseWheel: {
			notifyListeners (SWT.MouseWheel, event);
			event.type = SWT.None;
			if (isDisposed ()) break;
			if (!event.doit) break;
			if (event.count != 0) {
				event.doit = false;
				int oldIndex = getSelectionIndex ();
				if (event.count > 0) {
					select (Math.max (oldIndex - 1, 0));
				} else {
					select (Math.min (oldIndex + 1, getItemCount () - 1));
				}
				if (oldIndex != getSelectionIndex ()) {
					Event e = new Event();
					e.time = event.time;
					e.stateMask = event.stateMask;
					notifyListeners (SWT.Selection, e);
				}
				if (isDisposed ()) break;
			}
			break;
		}
		case SWT.Traverse: {
			switch (event.detail) {
				case SWT.TRAVERSE_ARROW_PREVIOUS:
				case SWT.TRAVERSE_ARROW_NEXT:
					// The enter causes default selection and
					// the arrow keys are used to manipulate the list contents so
					// do not use them for traversal.
					event.doit = false;
					break;
				case SWT.TRAVERSE_TAB_PREVIOUS:
					event.doit = traverse(SWT.TRAVERSE_TAB_PREVIOUS);
					event.detail = SWT.TRAVERSE_NONE;
					return;
			}
			Event e = new Event ();
			e.time = event.time;
			e.detail = event.detail;
			e.doit = event.doit;
			e.character = event.character;
			e.keyCode = event.keyCode;
			e.keyLocation = event.keyLocation;
			notifyListeners (SWT.Traverse, e);
			event.doit = e.doit;
			event.detail = e.detail;
			break;
		}
		case SWT.Verify: {
			Event e = new Event ();
			e.text = event.text;
			e.start = event.start;
			e.end = event.end;
			e.character = event.character;
			e.keyCode = event.keyCode;
			e.keyLocation = event.keyLocation;
			e.stateMask = event.stateMask;
			notifyListeners (SWT.Verify, e);
			event.text = e.text;
			event.doit = e.doit;
			break;
		}
	}
}
@Override
public boolean traverse(int event){
	/*
	 * When the traverse event is sent to the CCombo, it will create a list of
	 * controls to tab to next. Since the CCombo is a composite, the next control is
	 * the Text field which is a child of the CCombo. It will set focus to the text
	 * field which really is itself. So, call the traverse next events directly on the text.
	 */
	if (event == SWT.TRAVERSE_ARROW_NEXT || event == SWT.TRAVERSE_TAB_NEXT) {
		return text.traverse(event);
	}
	return super.traverse(event);
}
}