well if your idea is completely ludicrously over the top you could run into the bmpman image file limit of IIRC the upper 4000s. I'm not sure what the rule is for images overlapping, either- if a looping animation covers part of an interactive animation, or even another looping animation, does FS know what to do with it? With new PNG and 8-bit transparency (as opposed to ani's 1-bit transparency which in most cases would look fugly if actually visible) support, it may be possible to overlay images on top of one another in the mainhall. Then again, this may be completely unsupported.