Straight to your questions:
- This is due to the way browsers work. Since the image file is not a page, it does not have a title and Firefox forces the image's name to be shown in RadWindow's titlebar. You can avoid this by setting the title of the dialog in OnClientShow (a small timeout may be needed).
- The behavior is actually due to a problem with RadWindow's black skin and we are working on fixing it - IE shows the expected behavior. If, however you want to change the iframe's background in IE as well, I suggest to use the following code (hooked to the OnClientShow property)
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