examples/org.eclipse.swt.examples/src/org/eclipse/swt/examples/hoverhelp/HoverHelp.java - platform/eclipse.platform.swt - Git at Google

 /*******************************************************************************
  * Copyright (c) 2000, 2016 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.examples.hoverhelp;


 import java.io.IOException;
 import java.io.InputStream;
 import java.text.MessageFormat;
 import java.util.MissingResourceException;
 import java.util.ResourceBundle;

 import org.eclipse.swt.SWT;
 import org.eclipse.swt.events.MouseAdapter;
 import org.eclipse.swt.events.MouseEvent;
 import org.eclipse.swt.events.MouseTrackAdapter;
 import org.eclipse.swt.graphics.Image;
 import org.eclipse.swt.graphics.ImageData;
 import org.eclipse.swt.graphics.Point;
 import org.eclipse.swt.graphics.Rectangle;
 import org.eclipse.swt.layout.FillLayout;
 import org.eclipse.swt.layout.GridData;
 import org.eclipse.swt.layout.GridLayout;
 import org.eclipse.swt.widgets.Button;
 import org.eclipse.swt.widgets.Composite;
 import org.eclipse.swt.widgets.Control;
 import org.eclipse.swt.widgets.Display;
 import org.eclipse.swt.widgets.Item;
 import org.eclipse.swt.widgets.Label;
 import org.eclipse.swt.widgets.Shell;
 import org.eclipse.swt.widgets.Table;
 import org.eclipse.swt.widgets.TableItem;
 import org.eclipse.swt.widgets.ToolBar;
 import org.eclipse.swt.widgets.ToolItem;
 import org.eclipse.swt.widgets.Tree;
 import org.eclipse.swt.widgets.TreeItem;
 import org.eclipse.swt.widgets.Widget;
 /**
  * This example demonstrates how to implement hover help feedback
  * using the MouseTrackListener.
  */
 public class HoverHelp {
 	private static ResourceBundle resourceBundle = ResourceBundle.getBundle("examples_hoverhelp");

 	static final int
 		hhiInformation = 0,
 		hhiWarning = 1;
 	static final String[] imageLocations = {
 		"information.gif",
 		"warning.gif"
 	};
 	Image images[];

 	/**
 	 * Runs main program.
 	 */
 	public static void main (String [] args) {
 		Display display = new Display();
 		Shell shell = new HoverHelp().open(display);
 		// Event loop
 		while (shell != null && ! shell.isDisposed()) {
 			if (! display.readAndDispatch()) display.sleep();
 		}
 		// Cleanup
 		display.dispose();

 	}

 	/**
 	 * Opens the main program.
 	 */
 	public Shell open(Display display) {
 		// Load the images
 		Class<HoverHelp> clazz = HoverHelp.class;
 		try {
 			if (images == null) {
 				images = new Image[imageLocations.length];

 				for (int i = 0; i < imageLocations.length; ++i) {
 					InputStream stream = clazz.getResourceAsStream(imageLocations[i]);
 					ImageData source = new ImageData(stream);
 					ImageData mask = source.getTransparencyMask();
 					images[i] = new Image(display, source, mask);
 					try {
 						stream.close();
 					} catch (IOException e) {
 						e.printStackTrace();
 					}
 				}
 			}
 		} catch (Exception ex) {
 			System.err.println(getResourceString("error.CouldNotLoadResources",
 				new Object[] { ex.getMessage() }));
 			return null;
 		}

 		// Create the window
 		Shell shell = new Shell();
 		createPartControl(shell);
 		shell.addDisposeListener(e -> {
 			/* Free resources */
 			if (images != null) {
 				for (int i = 0; i < images.length; i++) {
 					final Image image = images[i];
 					if (image != null) image.dispose();
 				}
 				images = null;
 			}
 		});
 		shell.pack();
 		shell.open();
 		return shell;
 	}

 	/**
 	 * Gets a string from the resource bundle.
 	 * We don't want to crash because of a missing String.
 	 * Returns the key if not found.
 	 */
 	public String getResourceString(String key) {
 		try {
 			return resourceBundle.getString(key);
 		} catch (MissingResourceException e) {
 			return key;
 		} catch (NullPointerException e) {
 			return "!" + key + "!";
 		}
 	}

 	/**
 	 * Gets a string from the resource bundle and binds it
 	 * with the given arguments. If the key is not found,
 	 * return the key.
 	 */
 	public String getResourceString(String key, Object[] args) {
 		try {
 			return MessageFormat.format(getResourceString(key), args);
 		} catch (MissingResourceException e) {
 			return key;
 		} catch (NullPointerException e) {
 			return "!" + key + "!";
 		}
 	}

 	/**
 	 * Creates the example
 	 */
 	public void createPartControl(Composite frame) {
 		final ToolTipHandler tooltip = new ToolTipHandler(frame.getShell());

 		GridLayout layout = new GridLayout();
 		layout.numColumns = 3;
 		frame.setLayout(layout);

 		String platform = SWT.getPlatform();
 		String helpKey = "F1";
 		if (platform.equals("gtk")) helpKey = "Ctrl+F1";
 		if (platform.equals("cocoa")) helpKey = "Help";

 		ToolBar bar = new ToolBar (frame, SWT.BORDER);
 		for (int i=0; i<5; i++) {
 			ToolItem item = new ToolItem (bar, SWT.PUSH);
 			item.setText (getResourceString("ToolItem.text", new Object[] { Integer.valueOf(i) }));
 			item.setData ("TIP_TEXT", getResourceString("ToolItem.tooltip",
 				new Object[] { item.getText(), helpKey }));
 			item.setData ("TIP_HELPTEXTHANDLER", new ToolTipHelpTextHandler() {
 				@Override
 				public String getHelpText(Widget widget) {
 					Item item = (Item) widget;
 					return getResourceString("ToolItem.help", new Object[] { item.getText() });
 				}
 			});
 		}
 		GridData gridData = new GridData();
 		gridData.horizontalSpan = 3;
 		bar.setLayoutData(gridData);
 		tooltip.activateHoverHelp(bar);

 		Table table = new Table (frame, SWT.BORDER);
 		for (int i=0; i<4; i++) {
 			TableItem item = new TableItem (table, SWT.PUSH);
 			item.setText (getResourceString("Item", new Object[] { Integer.valueOf(i) }));
 			item.setData ("TIP_IMAGE", images[hhiInformation]);
 			item.setText (getResourceString("TableItem.text", new Object[] { Integer.valueOf(i) }));
 			item.setData ("TIP_TEXT", getResourceString("TableItem.tooltip",
 				new Object[] { item.getText(), helpKey }));
 			item.setData ("TIP_HELPTEXTHANDLER", new ToolTipHelpTextHandler() {
 				@Override
 				public String getHelpText(Widget widget) {
 					Item item = (Item) widget;
 					return getResourceString("TableItem.help", new Object[] { item.getText() });
 				}
 			});
 		}
 		table.setLayoutData(new GridData(GridData.VERTICAL_ALIGN_FILL));
 		tooltip.activateHoverHelp(table);

 		Tree tree = new Tree (frame, SWT.BORDER);
 		for (int i=0; i<4; i++) {
 			TreeItem item = new TreeItem (tree, SWT.PUSH);
 			item.setText (getResourceString("Item", new Object[] { Integer.valueOf(i) }));
 			item.setData ("TIP_IMAGE", images[hhiWarning]);
 			item.setText (getResourceString("TreeItem.text", new Object[] { Integer.valueOf(i) }));
 			item.setData ("TIP_TEXT", getResourceString("TreeItem.tooltip",
 				new Object[] { item.getText(), helpKey}));
 			item.setData ("TIP_HELPTEXTHANDLER", new ToolTipHelpTextHandler() {
 				@Override
 				public String getHelpText(Widget widget) {
 					Item item = (Item) widget;
 					return getResourceString("TreeItem.help", new Object[] { item.getText() });
 				}
 			});
 		}
 		tree.setLayoutData(new GridData(GridData.VERTICAL_ALIGN_FILL));
 		tooltip.activateHoverHelp(tree);

 		Button button = new Button (frame, SWT.PUSH);
 		button.setText (getResourceString("Hello.text"));
 		button.setData ("TIP_TEXT", getResourceString("Hello.tooltip"));
 		tooltip.activateHoverHelp(button);
 	}

 	/**
 	 * Emulated tooltip handler
 	 * Notice that we could display anything in a tooltip besides text and images.
 	 * For instance, it might make sense to embed large tables of data or buttons linking
 	 * data under inspection to material elsewhere, or perform dynamic lookup for creating
 	 * tooltip text on the fly.
 	 */
 	protected static class ToolTipHandler {
 		private Shell  parentShell;
 		private Shell  tipShell;
 		private Label  tipLabelImage, tipLabelText;
 		private Widget tipWidget; // widget this tooltip is hovering over
 		private Point  tipPosition; // the position being hovered over

 		/**
 		 * Creates a new tooltip handler
 		 *
 		 * @param parent the parent Shell
 		 */
 		public ToolTipHandler(Shell parent) {
 			final Display display = parent.getDisplay();
 			this.parentShell = parent;

 			tipShell = new Shell(parent, SWT.ON_TOP | SWT.TOOL);
 			GridLayout gridLayout = new GridLayout();
 			gridLayout.numColumns = 2;
 			gridLayout.marginWidth = 2;
 			gridLayout.marginHeight = 2;
 			tipShell.setLayout(gridLayout);

 			tipShell.setBackground(display.getSystemColor(SWT.COLOR_INFO_BACKGROUND));

 			tipLabelImage = new Label(tipShell, SWT.NONE);
 			tipLabelImage.setForeground(display.getSystemColor(SWT.COLOR_INFO_FOREGROUND));
 			tipLabelImage.setBackground(display.getSystemColor(SWT.COLOR_INFO_BACKGROUND));
 			tipLabelImage.setLayoutData(new GridData(GridData.FILL_HORIZONTAL |
 				GridData.VERTICAL_ALIGN_CENTER));

 			tipLabelText = new Label(tipShell, SWT.NONE);
 			tipLabelText.setForeground(display.getSystemColor(SWT.COLOR_INFO_FOREGROUND));
 			tipLabelText.setBackground(display.getSystemColor(SWT.COLOR_INFO_BACKGROUND));
 			tipLabelText.setLayoutData(new GridData(GridData.FILL_HORIZONTAL |
 				GridData.VERTICAL_ALIGN_CENTER));
 		}

 		/**
 		 * Enables customized hover help for a specified control
 		 *
 		 * @control the control on which to enable hoverhelp
 		 */
 		public void activateHoverHelp(final Control control) {
 			/*
 			 * Get out of the way if we attempt to activate the control underneath the tooltip
 			 */
 			control.addMouseListener(new MouseAdapter () {
 				@Override
 				public void mouseDown (MouseEvent e) {
 					if (tipShell.isVisible()) tipShell.setVisible(false);
 				}
 			});

 			/*
 			 * Trap hover events to pop-up tooltip
 			 */
 			control.addMouseTrackListener(new MouseTrackAdapter () {
 				@Override
 				public void mouseExit(MouseEvent e) {
 					if (tipShell.isVisible()) tipShell.setVisible(false);
 					tipWidget = null;
 				}
 				@Override
 				public void mouseHover (MouseEvent event) {
 					Point pt = new Point (event.x, event.y);
 					Widget widget = event.widget;
 					if (widget instanceof ToolBar) {
 						ToolBar w = (ToolBar) widget;
 						widget = w.getItem (pt);
 					}
 					if (widget instanceof Table) {
 						Table w = (Table) widget;
 						widget = w.getItem (pt);
 					}
 					if (widget instanceof Tree) {
 						Tree w = (Tree) widget;
 						widget = w.getItem (pt);
 					}
 					if (widget == null) {
 						tipShell.setVisible(false);
 						tipWidget = null;
 						return;
 					}
 					if (widget == tipWidget) return;
 					tipWidget = widget;
 					tipPosition = control.toDisplay(pt);
 					String text = (String) widget.getData("TIP_TEXT");
 					Image image = (Image) widget.getData("TIP_IMAGE");
 					tipLabelText.setText(text != null ? text : "");
 					tipLabelImage.setImage(image); // accepts null
 					tipShell.pack();
 					setHoverLocation(tipShell, tipPosition);
 					tipShell.setVisible(true);
 				}
 			});

 			/*
 			 * Trap F1 Help to pop up a custom help box
 			 */
 			control.addHelpListener(event -> {
 				if (tipWidget == null) return;
 				ToolTipHelpTextHandler handler = (ToolTipHelpTextHandler)
 					tipWidget.getData("TIP_HELPTEXTHANDLER");
 				if (handler == null) return;
 				String text = handler.getHelpText(tipWidget);
 				if (text == null) return;

 				if (tipShell.isVisible()) {
 					tipShell.setVisible(false);
 					Shell helpShell = new Shell(parentShell, SWT.SHELL_TRIM);
 					helpShell.setLayout(new FillLayout());
 					Label label = new Label(helpShell, SWT.NONE);
 					label.setText(text);
 					helpShell.pack();
 					setHoverLocation(helpShell, tipPosition);
 					helpShell.open();
 				}
 			});
 		}

 		/**
 		 * Sets the location for a hovering shell
 		 * @param shell the object that is to hover
 		 * @param position the position of a widget to hover over
 		 * @return the top-left location for a hovering box
 		 */
 		private void setHoverLocation(Shell shell, Point position) {
 			Rectangle displayBounds = shell.getDisplay().getBounds();
 			Rectangle shellBounds = shell.getBounds();
 			shellBounds.x = Math.max(Math.min(position.x, displayBounds.width - shellBounds.width), 0);
 			shellBounds.y = Math.max(Math.min(position.y + 16, displayBounds.height - shellBounds.height), 0);
 			shell.setBounds(shellBounds);
 		}
 	}

 	/**
 	 * ToolTip help handler
 	 */
 	protected interface ToolTipHelpTextHandler {
 		/**
 		 * Get help text
 		 * @param widget the widget that is under help
 		 * @return a help text string
 		 */
 		public String getHelpText(Widget widget);
 	}
 }
	/*******************************************************************************
	* Copyright (c) 2000, 2016 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.examples.hoverhelp;


	import java.io.IOException;
	import java.io.InputStream;
	import java.text.MessageFormat;
	import java.util.MissingResourceException;
	import java.util.ResourceBundle;

	import org.eclipse.swt.SWT;
	import org.eclipse.swt.events.MouseAdapter;
	import org.eclipse.swt.events.MouseEvent;
	import org.eclipse.swt.events.MouseTrackAdapter;
	import org.eclipse.swt.graphics.Image;
	import org.eclipse.swt.graphics.ImageData;
	import org.eclipse.swt.graphics.Point;
	import org.eclipse.swt.graphics.Rectangle;
	import org.eclipse.swt.layout.FillLayout;
	import org.eclipse.swt.layout.GridData;
	import org.eclipse.swt.layout.GridLayout;
	import org.eclipse.swt.widgets.Button;
	import org.eclipse.swt.widgets.Composite;
	import org.eclipse.swt.widgets.Control;
	import org.eclipse.swt.widgets.Display;
	import org.eclipse.swt.widgets.Item;
	import org.eclipse.swt.widgets.Label;
	import org.eclipse.swt.widgets.Shell;
	import org.eclipse.swt.widgets.Table;
	import org.eclipse.swt.widgets.TableItem;
	import org.eclipse.swt.widgets.ToolBar;
	import org.eclipse.swt.widgets.ToolItem;
	import org.eclipse.swt.widgets.Tree;
	import org.eclipse.swt.widgets.TreeItem;
	import org.eclipse.swt.widgets.Widget;
	/**
	* This example demonstrates how to implement hover help feedback
	* using the MouseTrackListener.
	*/
	public class HoverHelp {
	private static ResourceBundle resourceBundle = ResourceBundle.getBundle("examples_hoverhelp");

	static final int
	hhiInformation = 0,
	hhiWarning = 1;
	static final String[] imageLocations = {
	"information.gif",
	"warning.gif"
	};
	Image images[];

	/**
	* Runs main program.
	*/
	public static void main (String [] args) {
	Display display = new Display();
	Shell shell = new HoverHelp().open(display);
	// Event loop
	while (shell != null && ! shell.isDisposed()) {
	if (! display.readAndDispatch()) display.sleep();
	}
	// Cleanup
	display.dispose();

	}

	/**
	* Opens the main program.
	*/
	public Shell open(Display display) {
	// Load the images
	Class<HoverHelp> clazz = HoverHelp.class;
	try {
	if (images == null) {
	images = new Image[imageLocations.length];

	for (int i = 0; i < imageLocations.length; ++i) {
	InputStream stream = clazz.getResourceAsStream(imageLocations[i]);
	ImageData source = new ImageData(stream);
	ImageData mask = source.getTransparencyMask();
	images[i] = new Image(display, source, mask);
	try {
	stream.close();
	} catch (IOException e) {
	e.printStackTrace();
	}
	}
	}
	} catch (Exception ex) {
	System.err.println(getResourceString("error.CouldNotLoadResources",
	new Object[] { ex.getMessage() }));
	return null;
	}

	// Create the window
	Shell shell = new Shell();
	createPartControl(shell);
	shell.addDisposeListener(e -> {
	/* Free resources */
	if (images != null) {
	for (int i = 0; i < images.length; i++) {
	final Image image = images[i];
	if (image != null) image.dispose();
	}
	images = null;
	}
	});
	shell.pack();
	shell.open();
	return shell;
	}

	/**
	* Gets a string from the resource bundle.
	* We don't want to crash because of a missing String.
	* Returns the key if not found.
	*/
	public String getResourceString(String key) {
	try {
	return resourceBundle.getString(key);
	} catch (MissingResourceException e) {
	return key;
	} catch (NullPointerException e) {
	return "!" + key + "!";
	}
	}

	/**
	* Gets a string from the resource bundle and binds it
	* with the given arguments. If the key is not found,
	* return the key.
	*/
	public String getResourceString(String key, Object[] args) {
	try {
	return MessageFormat.format(getResourceString(key), args);
	} catch (MissingResourceException e) {
	return key;
	} catch (NullPointerException e) {
	return "!" + key + "!";
	}
	}

	/**
	* Creates the example
	*/
	public void createPartControl(Composite frame) {
	final ToolTipHandler tooltip = new ToolTipHandler(frame.getShell());

	GridLayout layout = new GridLayout();
	layout.numColumns = 3;
	frame.setLayout(layout);

	String platform = SWT.getPlatform();
	String helpKey = "F1";
	if (platform.equals("gtk")) helpKey = "Ctrl+F1";
	if (platform.equals("cocoa")) helpKey = "Help";

	ToolBar bar = new ToolBar (frame, SWT.BORDER);
	for (int i=0; i<5; i++) {
	ToolItem item = new ToolItem (bar, SWT.PUSH);
	item.setText (getResourceString("ToolItem.text", new Object[] { Integer.valueOf(i) }));
	item.setData ("TIP_TEXT", getResourceString("ToolItem.tooltip",
	new Object[] { item.getText(), helpKey }));
	item.setData ("TIP_HELPTEXTHANDLER", new ToolTipHelpTextHandler() {
	@Override
	public String getHelpText(Widget widget) {
	Item item = (Item) widget;
	return getResourceString("ToolItem.help", new Object[] { item.getText() });
	}
	});
	}
	GridData gridData = new GridData();
	gridData.horizontalSpan = 3;
	bar.setLayoutData(gridData);
	tooltip.activateHoverHelp(bar);

	Table table = new Table (frame, SWT.BORDER);
	for (int i=0; i<4; i++) {
	TableItem item = new TableItem (table, SWT.PUSH);
	item.setText (getResourceString("Item", new Object[] { Integer.valueOf(i) }));
	item.setData ("TIP_IMAGE", images[hhiInformation]);
	item.setText (getResourceString("TableItem.text", new Object[] { Integer.valueOf(i) }));
	item.setData ("TIP_TEXT", getResourceString("TableItem.tooltip",
	new Object[] { item.getText(), helpKey }));
	item.setData ("TIP_HELPTEXTHANDLER", new ToolTipHelpTextHandler() {
	@Override
	public String getHelpText(Widget widget) {
	Item item = (Item) widget;
	return getResourceString("TableItem.help", new Object[] { item.getText() });
	}
	});
	}
	table.setLayoutData(new GridData(GridData.VERTICAL_ALIGN_FILL));
	tooltip.activateHoverHelp(table);

	Tree tree = new Tree (frame, SWT.BORDER);
	for (int i=0; i<4; i++) {
	TreeItem item = new TreeItem (tree, SWT.PUSH);
	item.setText (getResourceString("Item", new Object[] { Integer.valueOf(i) }));
	item.setData ("TIP_IMAGE", images[hhiWarning]);
	item.setText (getResourceString("TreeItem.text", new Object[] { Integer.valueOf(i) }));
	item.setData ("TIP_TEXT", getResourceString("TreeItem.tooltip",
	new Object[] { item.getText(), helpKey}));
	item.setData ("TIP_HELPTEXTHANDLER", new ToolTipHelpTextHandler() {
	@Override
	public String getHelpText(Widget widget) {
	Item item = (Item) widget;
	return getResourceString("TreeItem.help", new Object[] { item.getText() });
	}
	});
	}
	tree.setLayoutData(new GridData(GridData.VERTICAL_ALIGN_FILL));
	tooltip.activateHoverHelp(tree);

	Button button = new Button (frame, SWT.PUSH);
	button.setText (getResourceString("Hello.text"));
	button.setData ("TIP_TEXT", getResourceString("Hello.tooltip"));
	tooltip.activateHoverHelp(button);
	}

	/**
	* Emulated tooltip handler
	* Notice that we could display anything in a tooltip besides text and images.
	* For instance, it might make sense to embed large tables of data or buttons linking
	* data under inspection to material elsewhere, or perform dynamic lookup for creating
	* tooltip text on the fly.
	*/
	protected static class ToolTipHandler {
	private Shell parentShell;
	private Shell tipShell;
	private Label tipLabelImage, tipLabelText;
	private Widget tipWidget; // widget this tooltip is hovering over
	private Point tipPosition; // the position being hovered over

	/**
	* Creates a new tooltip handler
	*
	* @param parent the parent Shell
	*/
	public ToolTipHandler(Shell parent) {
	final Display display = parent.getDisplay();
	this.parentShell = parent;

	tipShell = new Shell(parent, SWT.ON_TOP \| SWT.TOOL);
	GridLayout gridLayout = new GridLayout();
	gridLayout.numColumns = 2;
	gridLayout.marginWidth = 2;
	gridLayout.marginHeight = 2;
	tipShell.setLayout(gridLayout);

	tipShell.setBackground(display.getSystemColor(SWT.COLOR_INFO_BACKGROUND));

	tipLabelImage = new Label(tipShell, SWT.NONE);
	tipLabelImage.setForeground(display.getSystemColor(SWT.COLOR_INFO_FOREGROUND));
	tipLabelImage.setBackground(display.getSystemColor(SWT.COLOR_INFO_BACKGROUND));
	tipLabelImage.setLayoutData(new GridData(GridData.FILL_HORIZONTAL \|
	GridData.VERTICAL_ALIGN_CENTER));

	tipLabelText = new Label(tipShell, SWT.NONE);
	tipLabelText.setForeground(display.getSystemColor(SWT.COLOR_INFO_FOREGROUND));
	tipLabelText.setBackground(display.getSystemColor(SWT.COLOR_INFO_BACKGROUND));
	tipLabelText.setLayoutData(new GridData(GridData.FILL_HORIZONTAL \|
	GridData.VERTICAL_ALIGN_CENTER));
	}

	/**
	* Enables customized hover help for a specified control
	*
	* @control the control on which to enable hoverhelp
	*/
	public void activateHoverHelp(final Control control) {
	/*
	* Get out of the way if we attempt to activate the control underneath the tooltip
	*/
	control.addMouseListener(new MouseAdapter () {
	@Override
	public void mouseDown (MouseEvent e) {
	if (tipShell.isVisible()) tipShell.setVisible(false);
	}
	});

	/*
	* Trap hover events to pop-up tooltip
	*/
	control.addMouseTrackListener(new MouseTrackAdapter () {
	@Override
	public void mouseExit(MouseEvent e) {
	if (tipShell.isVisible()) tipShell.setVisible(false);
	tipWidget = null;
	}
	@Override
	public void mouseHover (MouseEvent event) {
	Point pt = new Point (event.x, event.y);
	Widget widget = event.widget;
	if (widget instanceof ToolBar) {
	ToolBar w = (ToolBar) widget;
	widget = w.getItem (pt);
	}
	if (widget instanceof Table) {
	Table w = (Table) widget;
	widget = w.getItem (pt);
	}
	if (widget instanceof Tree) {
	Tree w = (Tree) widget;
	widget = w.getItem (pt);
	}
	if (widget == null) {
	tipShell.setVisible(false);
	tipWidget = null;
	return;
	}
	if (widget == tipWidget) return;
	tipWidget = widget;
	tipPosition = control.toDisplay(pt);
	String text = (String) widget.getData("TIP_TEXT");
	Image image = (Image) widget.getData("TIP_IMAGE");
	tipLabelText.setText(text != null ? text : "");
	tipLabelImage.setImage(image); // accepts null
	tipShell.pack();
	setHoverLocation(tipShell, tipPosition);
	tipShell.setVisible(true);
	}
	});

	/*
	* Trap F1 Help to pop up a custom help box
	*/
	control.addHelpListener(event -> {
	if (tipWidget == null) return;
	ToolTipHelpTextHandler handler = (ToolTipHelpTextHandler)
	tipWidget.getData("TIP_HELPTEXTHANDLER");
	if (handler == null) return;
	String text = handler.getHelpText(tipWidget);
	if (text == null) return;

	if (tipShell.isVisible()) {
	tipShell.setVisible(false);
	Shell helpShell = new Shell(parentShell, SWT.SHELL_TRIM);
	helpShell.setLayout(new FillLayout());
	Label label = new Label(helpShell, SWT.NONE);
	label.setText(text);
	helpShell.pack();
	setHoverLocation(helpShell, tipPosition);
	helpShell.open();
	}
	});
	}

	/**
	* Sets the location for a hovering shell
	* @param shell the object that is to hover
	* @param position the position of a widget to hover over
	* @return the top-left location for a hovering box
	*/
	private void setHoverLocation(Shell shell, Point position) {
	Rectangle displayBounds = shell.getDisplay().getBounds();
	Rectangle shellBounds = shell.getBounds();
	shellBounds.x = Math.max(Math.min(position.x, displayBounds.width - shellBounds.width), 0);
	shellBounds.y = Math.max(Math.min(position.y + 16, displayBounds.height - shellBounds.height), 0);
	shell.setBounds(shellBounds);
	}
	}

	/**
	* ToolTip help handler
	*/
	protected interface ToolTipHelpTextHandler {
	/**
	* Get help text
	* @param widget the widget that is under help
	* @return a help text string
	*/
	public String getHelpText(Widget widget);
	}
	}