The issue is simply this:
In Diablo 3 (And SC2 I believe too) in windowed mode or full screen windowed mode the option to change the game resolution os greyed out. Unable to change. So the only way to change this is to manually resize the window via dragging the edge and kinds guess your resolution. Or go edit the Diablo 3 preferences file to get an exact windowed resolution.
I edited the preferences file. I wanted 1600x900 in windowed mode. How can I do this?
In game? No. Can't change resolution for windowed mode.
Manually resize the window by the edges? Almost impossible to get exactly 1600x900 this way.
Edit the Diablo 3 preferences file? This works, but I should not have to edit a preferences file to do this.
In every other game in windowed mode in game I just go to the resolution menu in game and 2 seconds later I have the desired windowed mode game resolution I want. But for Diablo 3 I can not do this and I have to jump through hoops to get this achieved.
But I should be able to just go in game and pick the resolution I want to play windowed at. I should not be forced to edit the preferences file like I am now. This needs to be fixed.