Comment 9 for bug 710356

I agree with the new description, much clearer, many thanks Paul.
The issue also occurs when you drag a window to the screen edge, not just when you resize to the screen edge. As shown in my original screenshot, I dragged the firefox window on the right screen to the left edge which got "stuck" a few pixels short. I opened the terminal on the left screen to show that it's quite pronounced when you have dual displays.