I've tried this and that and google high and low but I cannot find the answer.
I'm running Ubuntu 18.04 under VirtualBox on MacOs High Sierra host.
When I type TAB-CMD I can switch between VirtualBox and other running MacOs applications. This is what I want.
But every second time I switch 'back' to VirtualBox from some MacOs application Ubuntu shows all Ubuntu windows side by side in miniaturised form and I need to click to the application window I want to bring forward / use.
And I would like to get rid of this (I don't even know the name of this feature which may explain why my googling has failed).
As it is now switching between MacOs and back to Ubuntu is way too bothersome.