Comment 7 for bug 1092166

This is very close to one of the things I worked on yesterday. The transitioning (move animation) code wasn't aware of the new position when docking was enabled, so the keyboard would sometimes switch back to the undocked position. With inactive transparency timer it would even flicker between docked and undocked position a couple of times. As you wrote, this only happened after changing the docking toggle.
I'll test on Arch anyway later for the XInput issues, so I'll try it again there.