D
After fiddling more I realized that it sometimes works the way I want it to work (just click away and the panel bar hides itself again) and sometimes the panel bar sticks permanently.
I found that clicking away from the panel does, indeed, hide the panel bar again (good.) Hitting the hotkey a second time to close it, however, re-enables the view setting on the panel bar, permanently revealing it.
So,
bookmark panel hotkey then click away works as intended
bookmark panel hotkey then bookmark panel hotkey a second time closes the bookmark panel while permanently revealing the panel bar
Not sure if this is intended or a bug now that I've discovered this behavior