One thing I could complain about is that it is difficult to scroll large attached or linked images as the forum software creates separate scroll bars for them. Thus I have a vertical scroll bar on the browser and vertical/horizontal scroll bars on the image(s). The problem is that all three aren't visible all the time and I have to move each one repeatedly to see all parts of the image. This can be a little frustrating.
However I don't know if there's anything you could do about it without changing the whole forum software.