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
titleImageLabel = new Label(parent, SWT.CENTER);
		titleImageLabel.setBackground(background);
		if (titleAreaImage == null)
			titleImageLabel.setImage(JFaceResources
					.getImage(DLG_IMG_TITLE_BANNER));
		else
			titleImageLabel.setImage(titleAreaImage);
		FormData imageData = new FormData();
		imageData.top = new FormAttachment(0, 0);
		
		
		
		
		
		imageData.right = new FormAttachment(100, 0); 
		titleImageLabel.setLayoutData(imageData);
		
		titleLabel = new Label(parent, SWT.LEFT);
		JFaceColors.setColors(titleLabel, foreground, background);
		titleLabel.setFont(JFaceResources.getBannerFont());
		titleLabel.setText(" ");
		FormData titleData = new FormData();
		titleData.top = new FormAttachment(0, verticalSpacing);
		titleData.right = new FormAttachment(titleImageLabel);
		titleData.left = new FormAttachment(0, horizontalSpacing);
		titleLabel.setLayoutData(titleData);
		
		messageImageLabel = new Label(parent, SWT.CENTER);
		messageImageLabel.setBackground(background);