WPF UserControl shows up blank everywhere except in the designer for the control itself

I have a WPF UserControl that shows up fine in the designer. 开发者_如何学PythonHowever, the UserControl shows up blank anywhere else! What is the cause of this?

The source is here: http://github.com/angelsl/NSMBWSaveEd (the usercontrol is Block2Editor)

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Oh, god... I finally found it. You have style in Themes\Generic.xaml which sets Template property for your Block2Editor control. Remove it and all be ok.