I was noticing that additionally to the problems with the RibbonGroupBox described in http://fluent.codeplex.com/Thread/View.aspx?ThreadId=213152 in a simple application the content of the RibbonGroupBox was not showing. Also DataTemplates definied in the
resources of ancestors were not applied...
I suspect that the reason is that in an ItemsControl the Items behave differently to the Children in a Panel in matters of resources... if i remember that correctly..
I was wondering why the RibbonGroupBox is derived from an ItemsControl since mostly you fill it manually with controls and would not make use of the item generation facilities...