This bug is relevant to any OS that has DWM. First, while you have DWM enabled, install this style with stylish: http://userstyles.org/styles/41182/firefox-7-about-blank-glass Then, go into fullscreen. You will now see what is hidden beneath the background in fullscreen. It is an aero window without the default caption buttons, and with them replaced by the custom ones. If you look closely, you can actually see the borders of the window they use. This proves that Firefox does in fact have the ability to remove the default aero caption buttons, all that is left is to create some sort of API for removing them. This would proove very useful for extension developers, and could also possibly be used while installing a persona, to give better looks (the current way of doing things does not look pretty at all with the personas; this would make it much more aesthetically pleasing), or with complete themes that retain aero which would allow more control over the window for the theme makers. This would nullify the "chromemargin" hack for removing the buttons that worked with pre-ff12, and would actually make them go away (no hiding them under something needed).

This could also help make more consistency in windows operating systems, as themes currently can remove caption buttons in windows basic, but NOT windows aero (without adding a background over the entire window, which is a workaround that should NOT have to be done when you already have the necessary things implemented to create an API for it).