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
title = "";
		titleLabel.setText(title);
	}
	/**
	 * Sets the title bar color for this dialog.
	 * 
	 * @param color
	 *            the title bar color
	 */
	public void setTitleAreaColor(RGB color) {
		titleAreaRGB = color;
	}
	/**
	 * Sets the title image to be shown in the title area of this dialog.
	 * 
	 * @param newTitleImage
	 *            the title image to be shown
	 */
	public void setTitleImage(Image newTitleImage) {
		titleAreaImage = newTitleImage;
		if (titleImageLabel != null) {
			titleImageLabel.setImage(newTitleImage);
			determineTitleImageLargest();
			Control top;
			if (titleImageLargest)
				top = titleImageLabel;
			else
				top = messageLabel;
			resetWorkAreaAttachments(top);
		}