So sometimes I'll maximize a shell or other window, and then it won't resize back to the original state. And sometimes the corner-grab with the mouse is tricky. Seems random.
An easy thing to do is to right-click on the window title, which brings up the small Openbox menu. Clicking on Resize allows me to resize the window a bit to where I can grab a corner and get back to normal.
Still getting used to LXQT / Openbox and like it. There's always ALT left-click sometimes. And the drastic xkill in another shell, but sometimes I forget.
Can't resize / minimize window grab and fix
Can't resize / minimize window grab and fix
That's a UNIX book - cool. -Garth