bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/MenuItem.java

/*******************************************************************************
 * Copyright (c) 2000, 2005 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
 *******************************************************************************/
package org.eclipse.swt.widgets;


import org.eclipse.swt.*;
import org.eclipse.swt.internal.*;
import org.eclipse.swt.internal.gtk.*;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.events.*;

/**
 * Instances of this class represent a selectable user interface object
 * that issues notification when pressed and released. 
 * <dl>
 * <dt><b>Styles:</b></dt>
 * <dd>CHECK, CASCADE, PUSH, RADIO, SEPARATOR</dd>
 * <dt><b>Events:</b></dt>
 * <dd>Arm, Help, Selection</dd>
 * </dl>
 * <p>
 * Note: Only one of the styles CHECK, CASCADE, PUSH, RADIO and SEPARATOR
 * may be specified.
 * </p><p>
 * IMPORTANT: This class is <em>not</em> intended to be subclassed.
 * </p>
 */
public class MenuItem extends Item {
	Menu parent, menu;
	int /*long*/ groupHandle;
	int accelerator;
	
/**
 * Constructs a new instance of this class given its parent
 * (which must be a <code>Menu</code>) and a style value
 * describing its behavior and appearance. The item is added
 * to the end of the items maintained by its parent.
 * <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 menu control which will be the parent of the new instance (cannot be null)
 * @param style the style of control 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>
 *    <li>ERROR_INVALID_SUBCLASS - if this class is not an allowed subclass</li>
 * </ul>
 *
 * @see SWT#CHECK
 * @see SWT#CASCADE
 * @see SWT#PUSH
 * @see SWT#RADIO
 * @see SWT#SEPARATOR
 * @see Widget#checkSubclass
 * @see Widget#getStyle
 */
public MenuItem (Menu parent, int style) {
	super (parent, checkStyle (style));
	this.parent = parent;
	createWidget (parent.getItemCount ());
}

/**
 * Constructs a new instance of this class given its parent
 * (which must be a <code>Menu</code>), a style value
 * describing its behavior and appearance, and the index
 * at which to place it in the items maintained by its parent.
 * <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 menu control which will be the parent of the new instance (cannot be null)
 * @param style the style of control to construct
 * @param index the index to store the receiver in its parent
 *
 * @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>
 *    <li>ERROR_INVALID_SUBCLASS - if this class is not an allowed subclass</li>
 * </ul>
 *
 * @see SWT#CHECK
 * @see SWT#CASCADE
 * @see SWT#PUSH
 * @see SWT#RADIO
 * @see SWT#SEPARATOR
 * @see Widget#checkSubclass
 * @see Widget#getStyle
 */
public MenuItem (Menu parent, int style, int index) {
	super (parent, checkStyle (style));
	this.parent = parent;
	int count = parent.getItemCount ();
	if (!(0 <= index && index <= count)) {
		error (SWT.ERROR_INVALID_RANGE);
	}
	createWidget (index);
}

void addAccelerator (int /*long*/ accelGroup) {
	updateAccelerator (accelGroup, true);
}

void addAccelerators (int /*long*/ accelGroup) {
	addAccelerator (accelGroup);
	if (menu != null) menu.addAccelerators (accelGroup);
}

/**
 * Adds the listener to the collection of listeners who will
 * be notified when the arm events are generated for the control, by sending
 * it one of the messages defined in the <code>ArmListener</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 ArmListener
 * @see #removeArmListener
 */
public void addArmListener (ArmListener listener) {
	checkWidget();
	if (listener == null) error (SWT.ERROR_NULL_ARGUMENT);
	TypedListener typedListener = new TypedListener (listener);
	addListener (SWT.Arm, typedListener);
}

/**
 * Adds the listener to the collection of listeners who will
 * be notified when the help events are generated for the control, by sending
 * it one of the messages defined in the <code>HelpListener</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 HelpListener
 * @see #removeHelpListener
 */
public void addHelpListener (HelpListener listener) {
	checkWidget();
	if (listener == null) error (SWT.ERROR_NULL_ARGUMENT);
	TypedListener typedListener = new TypedListener (listener);
	addListener (SWT.Help, typedListener);
}

/**
 * Adds the listener to the collection of listeners who will
 * be notified when the menu item is selected, by sending
 * it one of the messages defined in the <code>SelectionListener</code>
 * interface.
 * <p>
 * When <code>widgetSelected</code> is called, the stateMask field of the event object is valid.
 * <code>widgetDefaultSelected</code> is not called.
 * </p>
 *
 * @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 SelectionListener
 * @see #removeSelectionListener
 * @see SelectionEvent
 */
public void addSelectionListener (SelectionListener listener) {
	checkWidget();
	if (listener == null) error (SWT.ERROR_NULL_ARGUMENT);
	TypedListener typedListener = new TypedListener(listener);
	addListener (SWT.Selection,typedListener);
	addListener (SWT.DefaultSelection,typedListener);
}

static int checkStyle (int style) {
	return checkBits (style, SWT.PUSH, SWT.CHECK, SWT.RADIO, SWT.SEPARATOR, SWT.CASCADE, 0);
}

protected void checkSubclass () {
	if (!isValidSubclass ()) error (SWT.ERROR_INVALID_SUBCLASS);
}

void createHandle (int index) {
	state |= HANDLE;
	byte [] buffer = new byte [1];
	int bits = SWT.CHECK | SWT.RADIO | SWT.PUSH | SWT.SEPARATOR;
	switch (style & bits) {
		case SWT.SEPARATOR:
			handle = OS.gtk_separator_menu_item_new ();
			break;
		case SWT.RADIO:
			/*
			* Feature in GTK.  In GTK, radio button must always be part of
			* a radio button group.  In a GTK radio group, one button is always
			* selected.  This means that it is not possible to have a single
			* radio button that is unselected.  This is necessary to allow
			* applications to implement their own radio behavior or use radio
			* buttons outside of radio groups.  The fix is to create a hidden
			* radio button for each radio button we create and add them
			* to the same group.  This allows the visible button to be
			* unselected.
			*/
			groupHandle = OS.gtk_radio_menu_item_new (0);
			if (groupHandle == 0) error (SWT.ERROR_NO_HANDLES);
			OS.g_object_ref (groupHandle);
			OS.gtk_object_sink (groupHandle);
			int /*long*/ group = OS.gtk_radio_menu_item_get_group (groupHandle);
			handle = OS.gtk_radio_menu_item_new_with_label (group, buffer);
			break;
		case SWT.CHECK:
			handle = OS.gtk_check_menu_item_new_with_label (buffer);
			break;
		case SWT.PUSH:
		default:
			handle = OS.gtk_image_menu_item_new_with_label (buffer);
			break;
	}
	if (handle == 0) error (SWT.ERROR_NO_HANDLES);
	if ((style & SWT.SEPARATOR) == 0) {
		int /*long*/ label = OS.gtk_bin_get_child (handle);
		OS.gtk_accel_label_set_accel_widget (label, 0);
	}
	int /*long*/ parentHandle = parent.handle;
	boolean enabled = OS.GTK_WIDGET_SENSITIVE (parentHandle);     
	if (!enabled) OS.GTK_WIDGET_SET_FLAGS (parentHandle, OS.GTK_SENSITIVE);
	OS.gtk_menu_shell_insert (parentHandle, handle, index);
	if (!enabled) OS.GTK_WIDGET_UNSET_FLAGS (parentHandle, OS.GTK_SENSITIVE);
	OS.gtk_widget_show (handle);
}

void fixMenus (Decorations newParent) {
	if (menu != null) menu.fixMenus (newParent);
}

/**
 * Returns the widget accelerator.  An accelerator is the bit-wise
 * OR of zero or more modifier masks and a key. Examples:
 * <code>SWT.CONTROL | SWT.SHIFT | 'T', SWT.ALT | SWT.F2</code>.
 * The default value is zero, indicating that the menu item does
 * not have an accelerator.
 *
 * @return the accelerator or 0
 *
 * </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 getAccelerator () {
	checkWidget();
	return accelerator;
}

int /*long*/ getAccelGroup () {
	Menu menu = parent;
	while (menu != null && menu.cascade != null) {
		menu = menu.cascade.parent;
	}
	if (menu == null) return 0;
	Decorations shell = menu.parent;
	return shell.menuBar == menu ? shell.accelGroup : 0;
}

/*public*/ Rectangle getBounds () {
	checkWidget();
	if (!OS.GTK_WIDGET_MAPPED (handle)) {
		return new Rectangle (0, 0, 0, 0);
	}
	int x = OS.GTK_WIDGET_X (handle);
	int y = OS.GTK_WIDGET_Y (handle);
	int width = OS.GTK_WIDGET_WIDTH (handle);
	int height = OS.GTK_WIDGET_HEIGHT (handle);
	return new Rectangle (x, y, width, height);
}

/**
 * Returns <code>true</code> if the receiver is enabled, and
 * <code>false</code> otherwise. A disabled menu item is typically
 * not selectable from the user interface and draws with an
 * inactive or "grayed" look.
 *
 * @return the receiver's enabled 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>
 * 
 * @see #isEnabled
 */
public boolean getEnabled () {
	checkWidget();
	return OS.GTK_WIDGET_SENSITIVE (handle);
}

/**
 * Returns the receiver's cascade menu if it has one or null
 * if it does not. Only <code>CASCADE</code> menu items can have
 * a pull down menu. The sequence of key strokes, button presses 
 * and/or button releases that are used to request a pull down
 * menu is platform specific.
 *
 * @return the receiver's menu
 *
 * @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 Menu getMenu () {
	checkWidget();
	return menu;
}

/**
 * Returns the receiver's parent, which must be a <code>Menu</code>.
 *
 * @return the receiver's parent
 *
 * @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 Menu getParent () {
	checkWidget();
	return parent;
}

/**
 * Returns <code>true</code> if the receiver is selected,
 * and false otherwise.
 * <p>
 * When the receiver is of type <code>CHECK</code> or <code>RADIO</code>,
 * it is selected when it is checked.
 *
 * @return the selection 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>
 */
public boolean getSelection () {
	checkWidget();
	if ((style & (SWT.CHECK | SWT.RADIO)) == 0) return false;
	return OS.gtk_check_menu_item_get_active(handle);
}

int /*long*/ gtk_activate (int /*long*/ widget) {
	if ((style & SWT.CASCADE) != 0 && menu != null) return 0;
	/*
	* Bug in GTK.  When an ancestor menu is disabled and
	* the user types an accelerator key, GTK delivers the
	* the activate signal even though the menu item cannot
	* be invoked using the mouse.  The fix is to ignore activate
	* signals when an ancestor menu is disabled.
	*/
	if (!isEnabled ()) return 0;
	Event event = new Event ();
	int /*long*/ ptr = OS.gtk_get_current_event ();
	if (ptr != 0) {
		GdkEvent gdkEvent = new GdkEvent ();
		OS.memmove (gdkEvent, ptr, GdkEvent.sizeof);
		switch (gdkEvent.type) {
			case OS.GDK_KEY_PRESS:
			case OS.GDK_KEY_RELEASE: 
			case OS.GDK_BUTTON_PRESS:
			case OS.GDK_2BUTTON_PRESS: 
			case OS.GDK_BUTTON_RELEASE: {
				int [] state = new int [1];
				OS.gdk_event_get_state (ptr, state);
				setInputState (event, state [0]);
				break;
			}
		}
		OS.gdk_event_free (ptr);
	}
	if ((style & SWT.RADIO) != 0) {
		if ((parent.getStyle () & SWT.NO_RADIO_GROUP) == 0) {
			selectRadio ();
		}
	}
	postEvent (SWT.Selection, event);
	return 0;
}

int /*long*/ gtk_select (int /*long*/ item) {
	parent.selectedItem = this;
	sendEvent (SWT.Arm);
	return 0;
}

int /*long*/ gtk_show_help (int /*long*/ widget, int /*long*/ helpType) {
	boolean handled = hooks (SWT.Help);
	if (handled) {
		postEvent (SWT.Help);
	} else {
		handled = parent.sendHelpEvent (helpType);
	}
	if (handled) {
		OS.gtk_menu_shell_deactivate (parent.handle);
		return 1;
	}
	return 0;
}

void hookEvents () {
	super.hookEvents ();
	int /*long*/ windowProc2 = display.windowProc2;
	int /*long*/ windowProc3 = display.windowProc3;
	OS.g_signal_connect (handle, OS.activate, windowProc2, ACTIVATE);
	OS.g_signal_connect (handle, OS.select, windowProc2, SELECT);
	OS.g_signal_connect (handle, OS.show_help, windowProc3, SHOW_HELP);
}

/**
 * Returns <code>true</code> if the receiver is enabled and all
 * of the receiver's ancestors are enabled, and <code>false</code>
 * otherwise. A disabled menu item is typically not selectable from the
 * user interface and draws with an inactive or "grayed" look.
 *
 * @return the receiver's enabled 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>
 * 
 * @see #getEnabled
 */
public boolean isEnabled () {
	return getEnabled () && parent.isEnabled ();
}

void releaseChild () {
	super.releaseChild ();
	if (menu != null) {
		if (menu.selectedItem == this) menu.selectedItem = null;
		menu.dispose ();
	}
	menu = null;
}

void releaseWidget () {
	if (menu != null) menu.releaseResources ();
	menu = null;
	super.releaseWidget ();
	int /*long*/ accelGroup = getAccelGroup ();
	if (accelGroup != 0) removeAccelerator (accelGroup);
	if (groupHandle != 0) OS.g_object_unref (groupHandle);
	groupHandle = 0;
	accelerator = 0;
	parent = null;
}

void removeAccelerator (int /*long*/ accelGroup) {
	updateAccelerator (accelGroup, false);
}

void removeAccelerators (int /*long*/ accelGroup) {
	removeAccelerator (accelGroup);
	if (menu != null) menu.removeAccelerators (accelGroup);
}

/**
 * Removes the listener from the collection of listeners who will
 * be notified when the arm events are generated for the control.
 *
 * @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 ArmListener
 * @see #addArmListener
 */
public void removeArmListener (ArmListener listener) {
	checkWidget();
	if (listener == null) error (SWT.ERROR_NULL_ARGUMENT);
	if (eventTable == null) return;
	eventTable.unhook (SWT.Arm, listener);
}

/**
 * Removes the listener from the collection of listeners who will
 * be notified when the help events are generated for the control.
 *
 * @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 HelpListener
 * @see #addHelpListener
 */
public void removeHelpListener (HelpListener listener) {
	checkWidget();
	if (listener == null) error (SWT.ERROR_NULL_ARGUMENT);
	if (eventTable == null) return;
	eventTable.unhook (SWT.Help, listener);
}

/**
 * Removes the listener from the collection of listeners who will
 * be notified when the control is selected.
 *
 * @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) error (SWT.ERROR_NULL_ARGUMENT);
	if (eventTable == null) return;
	eventTable.unhook (SWT.Selection, listener);
	eventTable.unhook (SWT.DefaultSelection,listener);	
}
void selectRadio () {
	int index = 0;
	MenuItem [] items = parent.getItems ();
	while (index < items.length && items [index] != this) index++;
	int i = index - 1;
	while (i >= 0 && items [i].setRadioSelection (false)) --i;
	int j = index + 1;
	while (j < items.length && items [j].setRadioSelection (false)) j++;
	setSelection (true);
}
/**
 * Sets the widget accelerator.  An accelerator is the bit-wise
 * OR of zero or more modifier masks and a key. Examples:
 * <code>SWT.MOD1 | SWT.MOD2 | 'T', SWT.MOD3 | SWT.F2</code>.
 * <code>SWT.CONTROL | SWT.SHIFT | 'T', SWT.ALT | SWT.F2</code>.
 * The default value is zero, indicating that the menu item does
 * not have an accelerator.
 *
 * @param accelerator an integer that is the bit-wise OR of masks and a key
 *
 * </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 setAccelerator (int accelerator) {
	checkWidget();
	if (this.accelerator == accelerator) return;
	int /*long*/ accelGroup = getAccelGroup ();
	if (accelGroup != 0) removeAccelerator (accelGroup);
	this.accelerator = accelerator;
	if (accelGroup != 0) addAccelerator (accelGroup);
}

/**
 * Enables the receiver if the argument is <code>true</code>,
 * and disables it otherwise. A disabled menu item is typically
 * not selectable from the user interface and draws with an
 * inactive or "grayed" look.
 *
 * @param enabled the new enabled 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>
 */
public void setEnabled (boolean enabled) {
	checkWidget();
	if (OS.GTK_WIDGET_SENSITIVE (handle) == enabled) return;
	int /*long*/ accelGroup = getAccelGroup ();
	if (accelGroup != 0) removeAccelerator (accelGroup);
	OS.gtk_widget_set_sensitive (handle, enabled);
	if (accelGroup != 0) addAccelerator (accelGroup);
}

/**
 * Sets the image the receiver will display to the argument.
 * <p>
 * Note: This operation is a hint and is not supported on
 * platforms that do not have this concept (for example, Windows NT).
 * </p>
 *
 * @param image the image to display
 *
 * @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 setImage (Image image) {
	checkWidget();
	if ((style & SWT.SEPARATOR) != 0) return;
	super.setImage (image);
	if (!OS.GTK_IS_IMAGE_MENU_ITEM (handle)) return;
	if (image != null) {
		ImageList imageList = parent.imageList;
		if (imageList == null) imageList = parent.imageList = new ImageList ();
		int imageIndex = imageList.indexOf (image);
		if (imageIndex == -1) {
			imageIndex = imageList.add (image);
		} else {
			imageList.put (imageIndex, image);
		}
		int /*long*/ pixbuf = imageList.getPixbuf (imageIndex);
		int /*long*/ imageHandle = OS.gtk_image_new_from_pixbuf (pixbuf);
		OS.gtk_image_menu_item_set_image (handle, imageHandle);
		OS.gtk_widget_show (imageHandle);
	} else {
		OS.gtk_image_menu_item_set_image (handle, 0);
	}
}

/**
 * Sets the receiver's pull down menu to the argument.
 * Only <code>CASCADE</code> menu items can have a
 * pull down menu. The sequence of key strokes, button presses
 * and/or button releases that are used to request a pull down
 * menu is platform specific.
 *
 * @param menu the new pull down menu
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_MENU_NOT_DROP_DOWN - if the menu is not a drop down menu</li>
 *    <li>ERROR_MENUITEM_NOT_CASCADE - if the menu item is not a <code>CASCADE</code></li>
 *    <li>ERROR_INVALID_ARGUMENT - if the menu has been disposed</li>
 *    <li>ERROR_INVALID_PARENT - if the menu is not in the same widget tree</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 setMenu (Menu menu) {
	checkWidget ();

	/* Check to make sure the new menu is valid */
	if ((style & SWT.CASCADE) == 0) {
		error (SWT.ERROR_MENUITEM_NOT_CASCADE);
	}
	if (menu != null) {
		if ((menu.style & SWT.DROP_DOWN) == 0) {
			error (SWT.ERROR_MENU_NOT_DROP_DOWN);
		}
		if (menu.parent != parent.parent) {
			error (SWT.ERROR_INVALID_PARENT);
		}
	}

	/* Assign the new menu */
	Menu oldMenu = this.menu;
	if (oldMenu == menu) return;
	int /*long*/ accelGroup = getAccelGroup ();
	if (accelGroup != 0) removeAccelerators (accelGroup);
	if (oldMenu != null) {
		oldMenu.cascade = null;
		/*
		* Add a reference to the menu we are about
		* to replace or GTK will destroy it.
		*/
		OS.g_object_ref (oldMenu.handle);
		OS.gtk_menu_item_remove_submenu (handle);
	}
	if ((this.menu = menu) != null) {
		menu.cascade = this;
		OS.gtk_menu_item_set_submenu (handle, menu.handle);
	}
	if (accelGroup != 0) addAccelerators (accelGroup);
}

void setOrientation() {
	if ((parent.style & SWT.RIGHT_TO_LEFT) != 0) {
		if (handle != 0) {
			OS.gtk_widget_set_direction (handle, OS.GTK_TEXT_DIR_RTL);
			OS.gtk_container_forall (handle, display.setDirectionProc, OS.GTK_TEXT_DIR_RTL);		
		}
	}
}

boolean setRadioSelection (boolean value) {
	if ((style & SWT.RADIO) == 0) return false;
	if (getSelection () != value) {
		setSelection (value);
		postEvent (SWT.Selection);
	}
	return true;
}

/**
 * Sets the selection state of the receiver.
 * <p>
 * When the receiver is of type <code>CHECK</code> or <code>RADIO</code>,
 * it is selected when it is checked.
 *
 * @param selected the new selection 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>
 */
public void setSelection (boolean selected) {
	checkWidget();
	if ((style & (SWT.CHECK | SWT.RADIO)) == 0) return;
	OS.g_signal_handlers_block_matched (handle, OS.G_SIGNAL_MATCH_DATA, 0, 0, 0, 0, ACTIVATE);
	OS.gtk_check_menu_item_set_active (handle, selected);
	if ((style & SWT.RADIO) != 0) OS.gtk_check_menu_item_set_active (groupHandle, !selected);
	OS.g_signal_handlers_unblock_matched (handle, OS.G_SIGNAL_MATCH_DATA, 0, 0, 0, 0, ACTIVATE);
}

/**
 * Sets the receiver's text. The string may include
 * the mnemonic character and accelerator text.
 * <p>
 * Mnemonics are indicated by an '&amp' that causes the next
 * character to be the mnemonic.  When the user presses a
 * key sequence that matches the mnemonic, a selection
 * event occurs. On most platforms, the mnemonic appears
 * underlined but may be emphasised in a platform specific
 * manner.  The mnemonic indicator character '&amp' can be
 * escaped by doubling it in the string, causing a single
 *'&amp' to be displayed.
 * </p>
 * <p>
 * Accelerator text is indicated by the '\t' character.
 * On platforms that support accelerator text, the text
 * that follows the '\t' character is displayed to the user,
 * typically indicating the key stroke that will cause
 * the item to become selected.  On most platforms, the
 * accelerator text appears right aligned in the menu.
 * Setting the accelerator text does not install the
 * accelerator key sequence. The accelerator key sequence
 * is installed using #setAccelerator.
 * </p>
 * 
 * @param string the new text
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the text 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 #setAccelerator
 */
public void setText (String string) {
	checkWidget();
	if (string == null) error (SWT.ERROR_NULL_ARGUMENT);
	if ((style & SWT.SEPARATOR) != 0) return;
	if (text.equals (string)) return;
	super.setText (string);
	String accelString = "";
	int index = string.indexOf ('\t');
	if (index != -1) {
		accelString = string.substring (index, string.length());
		string = string.substring (0, index);
	}
	char [] chars = fixMnemonic (string);
	byte [] buffer = Converter.wcsToMbcs (null, chars, true);
	int /*long*/ label = OS.gtk_bin_get_child (handle);
	OS.gtk_label_set_text_with_mnemonic (label, buffer);
	buffer = Converter.wcsToMbcs (null, accelString, true);
	int /*long*/ ptr = OS.g_malloc (buffer.length);
	OS.memmove (ptr, buffer, buffer.length);
	int /*long*/ oldPtr = OS.GTK_ACCEL_LABEL_GET_ACCEL_STRING (label);
	OS.GTK_ACCEL_LABEL_SET_ACCEL_STRING (label, ptr);
	if (oldPtr != 0) OS.g_free (oldPtr);
}

void updateAccelerator (int /*long*/ accelGroup, boolean add) {
	if (accelerator == 0 || !getEnabled ()) return;
	int mask = 0;
	if ((accelerator & SWT.ALT) != 0) mask |= OS.GDK_MOD1_MASK;
	if ((accelerator & SWT.SHIFT) != 0) mask |= OS.GDK_SHIFT_MASK;
	if ((accelerator & SWT.CONTROL) != 0) mask |= OS.GDK_CONTROL_MASK;
	int keysym = accelerator & SWT.KEY_MASK;
	int newKey = Display.untranslateKey (keysym);
	if (newKey != 0) {
		keysym = newKey;
	} else {
		switch (keysym) {
			case '\r': keysym = OS.GDK_Return; break;
			default: keysym = Display.wcsToMbcs ((char) keysym);
		}
	}
	/* When accel_key is zero, it causes GTK warnings */
	if (keysym != 0) {
		if (add) {
			OS.gtk_widget_add_accelerator (handle, OS.activate, accelGroup, keysym, mask, OS.GTK_ACCEL_VISIBLE);
		} else {
			OS.gtk_widget_remove_accelerator (handle, accelGroup, keysym, mask);
		}
	}
}
}