"Save Windows Positions Now" doesn't seem to work for two monitors
I'd hate to interrupt your work on the next version of GIMP, but I thought you might want to know that there's a minor issue with the newest version which I downloaded today. When I reopen GIMP the main screen is minimised, and the Layers|Toolbox window is on the wrong screen, i.e. on the same screen as the minimised main window. "Open windows on the same monitor they were open before" is obviously turned on.
I half-suspect this has something to do with the fact that when I close GIMP, the application doesn't just go away, but an "empty" sort of GIMP remains that I need to then close again.
In the previous version the "Save Windows Positions Now" wasn't quite perfect either, as much as I'd hate to grumble about it, and the Layers|Toolbox window reopened "nudged" a few pixels bottom/right.
Hope this helps you improve GIMP even further. All the best!