@baris 馃憤
Cool, I can't remember where or if but I'm sure I suggested this a long time ago so I was delighted to see. Which means I think it should be a UI behaviour in core. 馃檪
I've tweaked it to double click, it differentiates the actions of what UI single clicks are reserved for, buttons/links. It's also easy to trigger it by mistake with a single click configuration.
How I really envisaged it was asymmetrical expand and collapse. SO the user can target one panel or the other quickly as they prefer.
I would also favour a dblclick for single panel expand/collapse.
So you can have one or the other setup, or if you wanted both. Then what you might try to implement is to create two zones, halves, and assign top half as asymmetrical action, and bottom half symmetrical action for some UI mystery UX.