Collapsed State - controls missing in popup

I have a RibbonGroup that has a Frame and a Button control. When the group collapses and I click to get the popup, only the button control appears - the Frame control is missing. The behavior is also exhibited when using the WindowsFormHost control with a WebBrowser child. Is this a bug or am I doing something incorrectly?
Thanks,
Mike

If you're hosting HTML content in the frame, it's functionally identical to a WebBrowse hosted in a WindowsFormsHost. This is a bug, but not in SandRibbon. Support for hosting Windows Forms content in WPF is buggy at best, and simply doesn't cope with dynamically showing and hiding very well at all.