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
private static final int H_GAP_IMAGE = 5;
	
	private static final int MIN_DIALOG_WIDTH = 350;
	
	private static final int MIN_DIALOG_HEIGHT = 150;
	private Label titleLabel;
	private Label titleImageLabel;
	private Label bottomFillerLabel;
	private Label leftFillerLabel;
	private RGB titleAreaRGB;
	Color titleAreaColor;
	private String message = ""; 
	private String errorMessage;
	private Text messageLabel;
	private Composite workArea;
	private Label messageImageLabel;
	private Image messageImage;
	private boolean showingError = false;
	private boolean titleImageLargest = true;
	private int messageLabelHeight;
	private Image titleAreaImage;
	/**
	 * Instantiate a new title area dialog.
	 * 
	 * @param parentShell
	 *            the parent SWT shell
	 */
	public TitleAreaDialog(Shell parentShell) {
		super(parentShell);
	}