Bug 35192 Dialog.applyDialogFont should protect itself against null arguments
RC2 Now that many plugins use this method to apply the dialog font to widgets the method should protect itself against null arguments. Normally clients create their widget tree in a method createControl and there are changes that the returned control might be null. Adding a statement Dialog.applyDialogFont (result) with result == null will result in new NPEs.
bundles/org.eclipse.jface/src/org/eclipse/jface/dialogs/Dialog.java
* @return the OK button or <code>null</code>
	 * 
	 * @see createButton
	 * @since 2.0
	 * @deprecated Use <code>getButton(IDialogConstants.OK_ID)</code> instead.
	 * 		This method will be removed soon.
	 */
	protected Button getOKButton() {
		return getButton(IDialogConstants.OK_ID);
	}
	/**
	 * Initializes the computation of horizontal and vertical dialog units
	 * based on the size of current font.
	 * <p>
	 * This method must be called before any of the dialog unit based
	 * conversion methods are called.
	 * </p>
	 *
	 * @param control a control from which to obtain the current font
	 */
	protected void initializeDialogUnits(Control control) {
		
		GC gc = new GC(control);
		gc.setFont(JFaceResources.getDialogFont());
		fontMetrics = gc.getFontMetrics();
		gc.dispose();
	}
	/**
	 * Notifies that the ok button of this dialog has been pressed.
	 * <p>