Hi, here's one of the bugs I was able to reproduce on a fresh portable install of v6.68. I'm posting it as a demonstration of the deeper issues that the windows screensets have.
Steps to reproduce:
1. Open a freshly installed portable Reaper instance
2. Press F11 to make it fullscreen
3. Close the mixer
4. Create a track
5. Draw in a MIDI item and open it in a MIDI editor
6. Dock the MIDI editor
7. Save windows screenset 1 with all options ticked (don't tick the auto-save option though)
8. Undock the MIDI editor and maximize it
9. Save a 2nd screenset with same options as the previous one.
10. Switch to the first screenset with the assigned keyboard shortcut to see that it works properly (the MIDI editor moves to the docker)
11. Switch to the second screenset with the assigned keyboard shortcut to see that iw works properly (the MIDI editor maximizes)
12. Switch back to the first screenset
13. Now undock the MIDI editor
14. Switch to the second screenset
15. Observe how the MIDI editor doesn't go to full screen but is now in a floating window.
I kindly ask you to look into this and other screensets issues where window's positions in dockers aren't remembered and where their docking/floating states aren't remembered. I haven't yet been able to consistently reproduce the issue where the window's position in dockers isn't remembered but it is something that occurs frequently enough that it's annoying and kills the workflow.
I'm on Windows 10 x64 & Reaper x64