This should be an easy one to fix (if even worth the effort). I tend to get open backpacks stuck behind the main inventory window. When this happens, doing another open on the backpack (or any other container) should move that container window to the top. Right now, if the container is already open but obscured, the open action doesn't do anything.
I'd probably prefer non-inventory windows to always be on top of the inventory window, but that's obviously a separate change and not necessarily the best want to handle the UI, just a preference of mine.
