So you've got two screens and want the mixer window maximized on the second one. You do the following:
1.a Undock the mixer window (as unattached docker windows can only be resized, but not maximized)
1.b Move the mixer window to the second screen (this is optional)
2. Maximize the mixer window
3. Press Shift+F8 to save it as screen set #2
4. Press F7 (untouched standard screen set)
5. Press F8 (screen set #2) - the mixer window is NOT maximized anymore ...
The following screenshots illustrate the issue.
It looks like this, when I save the screenset via Shift+F8:
https://stash.reaper.fm/9267/supposed.jpg
[IMG]http://img153.**************/img153/1467/supposed.th.jpg[/IMG]
When recalling the screenset by Pressing F7, then pressing F8, it looks like this:
https://stash.reaper.fm/9268/recall.jpg
[IMG]http://img34.**************/img34/6956/recallm.th.jpg[/IMG]
Problem exists up to v4.03pre4. Problem also exists in Reaper 3.xx builds.