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/PreferencePage.java
public void widgetSelected(SelectionEvent e) {
					performApply();
				}
			});
            applyButton.setEnabled(isValid());
            applyDialogFont(buttonBar);
        } else {
            /* Check if there are any other buttons on the button bar.
             * If not, throw away the button bar composite.  Otherwise
             * there is an unusually large button bar.
             */
            if (buttonBar.getChildren().length < 1)
                buttonBar.dispose();
        }
    }
	/**
	 * Create a message area for the receiver.
	 * @param content
	 */
	private void createMessageArea(Composite content) {
		
		messageArea = new MessageRegion();
		messageArea.createContents(content);
		GridData messageData = 
			new GridData(GridData.FILL_HORIZONTAL | GridData.GRAB_HORIZONTAL);
		messageArea.setMessageLayoutData(messageData);
		
	}
	/**
     * Apply the dialog font to the composite and it's children