Bug 336684 [JFace] NPE in Tray Dialog
bundles/org.eclipse.jface/src/org/eclipse/jface/dialogs/TrayDialog.java
* <p>
	 * Note: Trays may not be supported with all custom layouts on the dialog's
	 * Shell. To avoid problems, use a single outer <code>Composite</code> for
	 * your dialog area, and set your custom layout on that <code>Composite</code>.
	 * </p>
	 * 
	 * @see org.eclipse.jface.window.Window#getLayout()
	 * @return a newly created layout or <code>null</code> for no layout
	 */
	protected Layout getLayout() {
		GridLayout layout = (GridLayout)super.getLayout();
		layout.numColumns = 5;
		layout.horizontalSpacing = 0;
		return layout;
	}
	
	/**
	 * Returns the tray currently shown in the dialog, or <code>null</code>
	 * if there is no tray.
	 * 
	 * @return the dialog's current tray, or <code>null</code> if there is none
	 */
	public DialogTray getTray() {
		return tray;
	}
	
	/*
	 * Called when the help control is invoked. This emulates the keyboard
	 * context help behavior (e.g. F1 on Windows). It traverses the widget
	 * tree upward until it finds a widget that has a help listener on it,