[MonoDevelop] GtkFrame not working properly

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Ok so I'm using monodevelop from svn and i have a problem using
GtkFrames, here's how to reproduce it:

1. Create a new project
2. put a GtkFrame onto the main window and run the project, so far so good
3. now stick a widget like a  label inside the Frame and try running it again
4. on the console you will see the following error: Gtk-WARNING **:
Attempting to add a widget with type GtkLabel to a GtkFrame, but as a
GtkBin subclass a GtkFrame can only contain one widget at a time; it
already contains a widget of type GtkAlignment

any idea whats going on?