Hi Friends,
and again I come with something from the series “Question from real life of a long time linux user” 
My today’s issue is the following (and I am experiencing it every day).
I use Virtualbox a lot, mostly with running two guest machines (Win10 & Special Linux distro). I also are a huge fan of virtual desktops and the desktop environments’s shortcuts to switch between them.
I recently watched a kind of ad about Apple’s Parallels. The user there could just swipe with 3 ( I think it was three) Fingers to slide from Workspace 1 (MacOS) to Workspace 2 (it was Win10).
But we are Linux people, right? So the keyboard is our thing and I prefer much more to define a shortcut for workspace-switching.
Now the issue…:
When ever I work in a guest of Vbox, the keyboard is grabbed by it. The mouse is kind of “seamless”, yes… but whenever I want to use a keyboard shortcut of my HOST-Machine, I first have to press the Host-Key of Vbox (default : Right Cmd Key).
Dont understand me wrong. Its just a second and a single type, that I quick press Right-CMD and then for exmaple Cmd+Alt+Up/Down (which is my user defined shortcut for workspace switching). Its just one more single keypress, I know. But it would be sooo much more convenient if I could just tell Vbox’ es guest to igore Cmd+Alt+Left/Right and to directly hand this one to the host machine.
First of all. I Know… it was a big text… but its a big thing for me, personally, as I use this keyboard shortcuts 100x a day. Thats 300.000 / year 
And… perhaps if someone has an idea for a solution this could help other people.
I would be super happy if you would have a good solution / hack / workaround
Kind regards from Germany, and stay safe
Joe