Resizing firefox sandbox window

A quick note on resizing the sandbox window that firefox runs in. I assum that the sandbox sets some window hints (or something) that prevents the sandbox window from resizing. I don't know what the reason is behind this, but I have been using TWM, which I assume is too old to take any notice of whatever the more recent (openbox, metacity) wms pick up on and use as a cue to lock the window size. TWM will quite happily resize the sandbox window, and what's more firefox quite happily resizes in the window (mentioning which is the purpose of this post). Is there any real need to lock the size of a sandbox window? (Rhetorical question, for anyone who may care to take a second look at the issue.)