Ever wanted to have a Designer-Only properties, whose only purpose is to do something in Visual Studio? I guess you already almost know how to do this. Simply create a property with Getters / Setters and assign an Editor to it, but there are a few things you can do to enhance it. 

One of the things that affects the overall friendliness of your custom WPF controls - but you may not consider implementing it - is the design-time integration. With Cider continuing to exist in VS 2010, there's a lot of design-time functionality at your disposal. Since the model is different in Cider than creating designers for WinForm controls, I'm trying to shed some light on the subject.