Bug 93245 [Dialogs] Error messages show up in two locations in the properties dialog
Force an error message: 1) select a Java project 2) open the properties dialog 3) navigate to Java Compiler>Building 4) enable project specific settings 5) enter a letter into the maximum number of problems field ->the error message shows up at the bottom 6) resize the dialog ->the error message also shows up in the banner
bundles/org.eclipse.jface/src/org/eclipse/jface/preference/PreferenceDialog.java
*/
	public void setErrorMessage(String newErrorMessage) {
		if (newErrorMessage == null)
			messageArea.clearErrorMessage();
		else
			messageArea.updateText(newErrorMessage, IMessageProvider.ERROR);
	}
	/**
	 * Save the last known tree width.
	 * 
	 * @param width
	 *            the width.
	 */
	private void setLastTreeWidth(int width) {
		lastTreeWidth = width;
	}
	/**
	 * Sets whether a Help button is available for this dialog.
	 * <p>
	 * Clients must call this framework method before the dialog's control has
	 * been created.
	 * <p>
	 * 
	 * @param b
	 *            <code>true</code> to include a Help button, and
	 *            <code>false</code> to not include one (the default)
	 */
	public void setHelpAvailable(boolean b) {
		isHelpAvailable = b;
	}