VM keeps keyboard when switching to host

[Mellon]

I'm running a Windows 7 VM with guest addons installed in full screen mode on a Linux Mint Serena host. Mouse and keyboard integration are working well but whenever I minimize the VM to work on the host the keyboard keeps captured by the VM. I always have to click somewhere on the host screen to release the keyboard from the VM.

[Mellon]

I forgot to mention that the problem seems to occur only when I minimise the VM via keyboard shortcut (HOST + M).

[Mellon]

Please forget my first comment. The problem occurs regardless of the way of minimising the VM.

[Mellon]

Meanwhile I've found out that it seems to be an issue of Mint or Cinnamon. Applications are using to keep the focus on their panel symbols until one clicks on the desktop or on a different window.