Bug 336684 [JFace] NPE in Tray Dialog
bundles/org.eclipse.jface/src/org/eclipse/jface/dialogs/TrayDialog.java
if (fHelpButton != null) {
			fHelpButton.setSelection(false);
		}
	}
	
	/**
	 * Returns true if the given Control is a direct or indirect child of
	 * container.
	 * 
	 * @param container
	 *            the potential parent
	 * @param control
	 * @return boolean <code>true</code> if control is a child of container
	 */
	private boolean isContained(Control container, Control control) {
		Composite parent;
		while ((parent = control.getParent()) != null) {
			if (parent == container) {
				return true;
			}
			control = parent;
		}
		return false;
	}
	/* (non-Javadoc)
	 * @see org.eclipse.jface.dialogs.Dialog#close()
	 */
	public boolean close() {
		/*
		 * Close the tray to ensure that those dialogs that remember their