Thanks for all the responses! Shift-F is not what I'm after. It sizes the project so the whole thing fits on the screen. What I want is for every track and folder to be shrunk to its minimum size. There is often a lot of blank space at the bottom this way. What I like is to be able to "reset" my brain, ask myself "ok, what exactly is it I have here?" Also it is useful for adding new tracks. If you hit Shift-F and then add a new track, it scrolls a little, which is annoying.
And I find no value at all in the ability to resize track folders. I only use them for organizational purposes, and the occasional folder-based solo and mute. I wish there was a way to tell Sonar that I never want folders to be any taller than the minimum. (Unrelated wish: I wish I could tell Sonar not to show the "Clip summaries" along the track folder. That just confuses me no end, as they look exactly like regular clips.)
The Ctrl-Up/Down arrows don't do what I'm after. Sometimes they only resize the selected tracks. If I Ctrl-Down to make the selected track taller, then do Ctrl-Up to shrink it, SOMETIMES that will make everything shrink, but just as often not. And sometimes tracks will shrink but not the folders they are in.
And yes, I have Auto Track Zoom turned off.