Key board shurtcuts not working when mintmenu or other applets are open

To reproduce the issue:

1. Click on the sound applet or open the mint menue, or maybe also any other cinnamon applet (but this I haven't tested yet)
2. Use keyboard shortcuts, or multimedia keys, which will not work correctly

What happens? Just some possibilities I tried...

• pressing left superkey used for the menu is triggered with some delay (around 2 sec.)
• pressing left superkey + D for desktop, opens the mint menu instead
• pressing multimedia key for sleep, does not trigger any operation at all
• pressing multimedia key for start/pause play, works only if the sound applet has been clicked and is open, when it is closed the music starts and after 1 sec. it stops again (It seems that the key click event is triggered twice with some delay)
• with sound applet open: mediakeys for volume work correctly (osd shown), but brightness (no osd) and sleep mode does not work

Please note, that all this keyboard shortcuts and mediakeys work correctly without any applet open.

The overall impression is that the whole behaviour is not consistent, some key-down events do not work correctly as for the superkey.

Hope my explanation was clear and helps to solve this issue.
Thanks for all your effort....

Reproduce the problem with the sound applet or mint menu open, then compare Super-key, desktop, multimedia, volume, brightness, and sleep behavior with no applet open. Trace the keyboard shortcut and applet event paths; done means these shortcuts and media keys behave consistently in both states without delayed or duplicated actions.