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
return true;
		else
			return currentPage.isValid();
	}
	/**
	 * @param control the <code>Control</code> to lay out.
	 * @since 3.0
	 */
	protected void layoutTreeAreaControl(Control control) {
		GridData gd = new GridData(GridData.FILL_VERTICAL);
		gd.widthHint = getLastTreeWidth();
		gd.verticalSpan = 1;
		control.setLayoutData(gd);
	}
	/**
	 * The preference dialog implementation of this <code>Dialog</code>
	 * framework method sends <code>performOk</code> to all pages of the 
	 * preference dialog, then calls <code>handleSave</code> on this dialog
	 * to save any state, and then calls <code>close</code> to close
	 * this dialog.
	 */
	protected void okPressed() {
		
		Iterator nodes = preferenceManager.getElements(PreferenceManager.PRE_ORDER).iterator();
		while (nodes.hasNext()) {
			IPreferenceNode node = (IPreferenceNode) nodes.next();
			IPreferencePage page = node.getPage();
			if (page != null) {
				if (!page.performOk())
					return;