Multimedia key acts on more than one app at the same time

User hits the play/pause multimedia key, while he has two apps opened: Chromium with a YouTube Video, and Goodvibes Radio Player. What happens is that both start / stop playing at the same time.

It seems that XFCE forwards the keystroke to both applications. Tested with chromium+goodvibes, and also chromium+vlc.

See https://gitlab.com/goodvibes/goodvibes/-/issues/129 for a detailed explanation