src/vs/workbench/contrib/preferences/browser/preferencesEditor.ts/DefaultPreferencesEditor/showReadonlyHint
class DefaultPreferencesEditor:	private showReadonlyHint(editor: ICodeEditor): void {
		const messageController = MessageController.get(editor);
		if (!messageController.isVisible()) {
			messageController.showMessage(nls.localize('defaultEditorReadonly', "Edit in the right hand side editor to override defaults."), editor.getSelection()!.getPosition());
		}
	}