Wasn't the same thing posted for MacOS a few days back, can't recall the name? Looking at the time on the repo makes me think the author pushed after seeing people requesting something similar for Linux.
That's not quite the same. With DeskPad you have to move the window to the virtual monitor. clipscreen allows you to select a portion of your screen without moving any windows.
edit: Here you go https://github.com/Stengo/DeskPad