Ach du Lieber is an expression in German. It's what you say when you can't believe something really lame has just happened, usually to you. Something like, you are trying to set up your Silverlight application for proper localization, but you keep running into gotchas that you really would have been expected to have been dealt with better by your development process, and your toolset in particular. This blog post runs through some of these localization gotchas. And, because I'm a nice guy who doesn't want everyone to share ALL my pain, it also includes a gotcha-avoiding checklist for localizing XAML in applications.