Bug 56637 [Preferences] DialogMessageArea image is too large
Is the background color of the error shown by DialogMessageArea to be changed? Or do you intend to leave it as it is right now? The error message looks a little out of place in the current implementation (being surrounded by white space).
bundles/org.eclipse.jface/src/org/eclipse/jface/preference/PreferenceDialog.java
final TreeViewer viewer = new TreeViewer(parent, SWT.BORDER);
		viewer.addPostSelectionChangedListener(new ISelectionChangedListener() {
			private void handleError() {
				try {
					 
					 
					
					viewer.removePostSelectionChangedListener(this);
					showPageFlippingAbortDialog();
					selectCurrentPageAgain();
					clearSelectedNode();
				} finally {
					viewer.addPostSelectionChangedListener(this);
				}
			}
			public void selectionChanged(SelectionChangedEvent event) {
				Object selection = getSingleSelection(event.getSelection());
				if (selection instanceof IPreferenceNode) {
					if (!isCurrentPageValid()) {
						handleError();
					} else if (!showPage((IPreferenceNode) selection)) {
						
						handleError();
					} else {
												
						lastSuccessfulNode = (IPreferenceNode) selection;
					}
					viewer.getControl().setFocus();
				}
			}