Undocking mixer from bottom panel sets size of bottom panel to full mixer

You know how adding the mixer to the bottom panel sets the latter's size to big enough to show the entire height of faders, taking over much of the screen?
If you subsequently reduce the bottom panel's height, then undock the mixer, the act of undocking resets the bottom panel height to "big enough for the mixer" again, even though the action we just did was making the bottom panel unrelated to the mixer.