OK, my Theme is finished (finally...!). But, guess what - I am still not able to take screenshots because the Theme wont load in window mode. What I found out about this Issue: It seems to be a Hardware issue. The Theme wont load in Window mode on my Cab and on my Laptop (Same error, see log.txt in first post). If I decrease the resolution in the Theme.ini the Theme loads in Window mode - but the Objects in the Theme are pretty messed up (clear, cause its a 1920x1080 Theme). If I set the resolution of the Theme to 1600x1080 and below, the Theme loads on my Laptop in window mode (still the error on my cab). If I set it to 1200x1080 and below, the Theme loads in window-mode on my Cab too....