Fullscreen Mode Blackens Other Monitor(s)
Was addressed already here: Re: Fullscreen mode with 2 monitors
But the solution, i.e. to globally set the "Displays have seperate Spaces" flag in mission control is not feasible at all - for all my other workflows requiring syncronized spaces over all monitors.
Severity is high: You basically can't watch e.g. a technical youtube video on one monitor and write notes on the second screen - since its black, shows only the mouse arrow.
Safari does the same.
But: In chrome it works nicely: Youtube goes to fullscreen, remaining the browser window on the space it was before and not shifting it to this full screen space, blackening out the others.
=> Is it feasible to get the behavior of Chrome also in Vivaldi, i.e. go Fullscreen but leave the window on the space it was before?