I have two monitors. When I maximize a window or make it full-screen, it occupies both monitors (i.e. the entire virtual desktop/screen). This is way too big, so I'd prefer that the window only occupy one monitor. Other window managers get this right already, so I'm guessing there's some protocol/extension that isn't implemented in blackbox.
Perhaps this issue is a feature request.
I'm currenty using blackbox version 0.72, commit 8c9e2af.