minimized Icon doesn't disappear when app closes

[HapFunMuff]

Reproduction
(1) Start up Bs Player and play a movie
(2) While movie is playing, press 'h' to hide the player controls.
(3) Now use 'alt-f4' to close the player down
(4) the minimized icon is still in the tray area.
(5) Run cursor over the tray to force a refresh which makes the icon disapper.

Expected
When you close the player with 'alt-f4' in the above state, the minimized icon should disappear. I believe this requires a self deregistration.

I can look into the coding of it if you want. At least the concept for it. Let me know.