2 monitors - snap to 'middle' edges - how?

i have searched and can not find an answer - so apologies if this has been asked before…

2 monitors side-by side

I know you can grab a window and move it to snap to half a monitor on the far left/right, but is there an easy way to have a window snap to the middle half of a monitor (eg: the left hand half of the right hand side monitor?)

I found some posts about windows (7?) being able to do it by using the alt+superkey. Is there a similar key combination available under mate?

thanks in anticipation