Ah, got it. Thank you very much.
By the way, I just tried cutting the screen to the right dimensions with a hot knife. The cutting itself was surprisingly easy, but it led to rims of some molten material on both sides of the screen. So I don't recommend this method to anyone else considering this, as it's almost impossible rasping the rims down to an equal level again without damaging the more central parts.
Anyway, there's still enough space left, so I'll try with a saw next. If all fails, I can still buy a new one.
Let's see, how it goes...