Bug 16995 HoverHelp example does not create ON_TOP Shell for tooltips
The shell created to show the tooltip does not have the ON_TOP style. It causes the main window to loose focus when the tooltip is shown.
examples/org.eclipse.swt.examples/src/org/eclipse/swt/examples/hoverhelp/HoverHelp.java
shell.addDisposeListener(new DisposeListener() {
			public void widgetDisposed(DisposeEvent e) {
				
				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 + "!";
		}			
	}