Docked Palette and Selection Filter panels cannot be closed during playback
During playback, when the Palette or Selection Filter panels are docked, the "close" and "undock" buttons at the top-right of either panel are grayed out and they do not respond to mouse events.
This is inconsistent with other docked panels and with undocked panels, all of which can be closed during playback.
The affected panels can still be undocked during playback by dragging their title bar. This also enables them to be closed.