It would be nice, at least for the linux version to have the ability to set different resolutions for Full Screen and Windowed modes. I cannot run Windowed mode with my optimal Full Screen Mode, and when I switch back, I either have a lower res than I want or the image goes off screen. I don't know if other OS's have the same problem or not.

My solution has been to change the Res each time I toggle between them which is a nuisance.

I think you can do this by setting specific mode-lines in your xorg.conf

Could make you a plugin that'd add a command to toggle between window at a specified res and fullscreen at another res.
Or possibly adjust it after you switch modes, but there's no specific way to detect mode switch, so can't just adjust it after you switch modes (say with alt enter) unless there's a check made periodically.
Tho i suppose a check every 0.5s wouldn't be much of a problem.

So would be nicer if devs did it i suppose.

I have been switching between full screen and window with no problems. Do you have your game setting set the same as your normal screen?

<shrug>

there wouldnt be any way for me to set say 850x1200 res? i sometimes put my moniter into picture-by-picture mode, and watch tv while semi idle in vo. sitting around waiting for something to happen or whatever.