Bug 249915 [Dialogs] TitleAreaDialog does not short circuit if message is null
M20080911-1700 When profiling use of a custom WizardDialog on Linux/GTK, a lot of time was spent in WizardPage.setMessage(...). It turns out that this was because we were setting a message of null after each keypress, and the page's description (DialogPage.getDescription()) was also null. In this case the short-circuit in TitleAreaDialog.setMessage(String, int) fails to notice that the message has not changed, and does a layout every time. For our dialog this takes about 40ms each time, which is noticeable when compounded with other work.
bundles/org.eclipse.jface/src/org/eclipse/jface/dialogs/TitleAreaDialog.java
/**
	 * Image registry key for error message image.
	 */
	public static final String DLG_IMG_TITLE_ERROR = DLG_IMG_MESSAGE_ERROR;
	/**
	 * Image registry key for banner image (value
	 * <code>"dialog_title_banner_image"</code>).
	 */
	public static final String DLG_IMG_TITLE_BANNER = "dialog_title_banner_image";
	/**
	 * Message type constant used to display an info icon with the message.
	 * 
	 * @since 2.0
	 * @deprecated
	 */
	public final static String INFO_MESSAGE = "INFO_MESSAGE"; 
	/**
	 * Message type constant used to display a warning icon with the message.
	 * 
	 * @since 2.0
	 * @deprecated
	 */
	public final static String WARNING_MESSAGE = "WARNING_MESSAGE";