This problem was introduced a few updates ago, and I keep hoping it'll get fixed. When I play in fullscreen, the background and characters/units twitch up and down on the screen, making it unplayable in that mode because of the eyestrain it causes. I had gotten used to windowed, albeit it with much annoyance on my part, but now, with the new Soul Armor icon, it cuts off the hero icon, forcing me to go to fullscreen to access it, causing even further irritation. Everything is out of wack in windowed mode, come to think of it, cutting off bits and pieces, but with most buttons partially clickable. I can stretch the window a bit before the fullscreen glitch occurs, but not enough to make much of a difference. Just talked to someone who is experiencing another problem, which is the icons being way too large and taking up too much of the screen.
Anyway, I might tinker with my video card settings to see if I can fix it, myself, but I'd rather the devs do it, since it could cause issues in other games for me, of which I currently have none (and I like it that way). I also did a clean install of GTarcade, removing the several hundred registry entries it likes to pile on, and all the folders it likes to hide (nearly all software does this now and I hates it, I do. Hates it), and during the very first loading of the game afterwards, fullscreen worked just fine until the next login.
"I have come to the conclusion that my subjective account of my own motivation is largely mythical on almost all occasions. I don't know why I do things."