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
* @see #setMinimumPageSize(int,int)
	 */
	public void setMinimumPageSize(Point size) {
		minimumPageSize.x = size.x;
		minimumPageSize.y = size.y;
	}
	/**
	 * Sets the preference store for this preference dialog.
	 *
	 * @param store the preference store
	 * @see #getPreferenceStore
	 */
	public void setPreferenceStore(IPreferenceStore store) {
		Assert.isNotNull(store);
		preferenceStore = store;
	}
	/**
	 * Save the currently selected node. 
	 */
	private void setSelectedNode() {
		String storeValue = null;
		IStructuredSelection selection = (IStructuredSelection) getTreeViewer().getSelection();
		if (selection.size() == 1) {
			IPreferenceNode node = (IPreferenceNode) selection.getFirstElement();
			storeValue = node.getId();
		}
		setSelectedNodePreference(storeValue);
	}
	/**
	 * Get the name of the selected item preference