My Module file
I misunderstood what you meant by the module file, you will find it attached.
I understand your point about the thumbnails only being image, but I would suggest changing them as it looks like you have a similar issue.
I don't think the module file is in error here if I replace the FramedPanel with any other panel it looks terrible but it is grey. It is only the framedPanel that is not applying the theme that shows up everywhere else in my application.
Thanks for your help the issue was the fact that my module file was missing the import
<inherits name='com.sencha.gxt.ui.GXT' />
Although you will not see it from the module file I sent you as I sent the wrong one. My application has 3 projects the entry point, the resources and the client. I was under the impression that the entry point was my controlling project but the theme for the frame come from the client project.