Clipman panel plugin incorrectly remembering mouse selections

[Matt Connell]

On Thu, 2023-05-25 at 17:11 +0200, Markus Hönicka wrote:
> Presumably because this is how copying with the mouse has always worked in X11? Mark something with the left mouse button, paste it somewhere else with the middle button.

Genuinely never knew this existed because I've never willingly middle-
clicked.  Can't do it without moving the scroll-wheel so I just trained
myself to forget it existed.