I was able to reproduce and fix an issue where specifically just the debugger popout window appears in the wrong place when the primary monitor is on the right and the secondary monitor is on the left and the debugger popout window is moved to the secondary monitor on the left. I can't see that there is any other issue affecting either the game preview window or if any of the editor bars are opened to a popup window, so if anyone thinks there's a separate issue with those, please file a new issue.