Today when revisiting the fluxbox manpage, I discovered this tip:

The maximize button (if present) maximizes / unmaximizes the window in three ways:

Button 1 (left mouse click) causes full screen maximization
button 2 (middle click) maximizes the window only vertically
button 3 (right click) maximizes the window only horizontally

Great tip.

I did not know that it was possible with a mouse.
looking at the keys file I could tell the function was there as I have them mapped to control alt enter for full max, control shift enter for vertically, and control super enter for horizontal.

Dave, your post reminded me of something I had intended to mention elsewhere:

antiX currently ships"wingrid" preinstalled and autostarted, and
its Ctrl+0 keybind is dangerous (that keybind should be outcommented) IMO.
If user slips, or loses track, and accidentally presses Ctrl+0 while focus is on the root window... BOOM, kills the window manager.
(leaving the user wondering"WTH just happened?!?")