Thanks guys!
It actually did not start trashing madly in the glass. Still, I'm not sure if they are bad at flying, or crashing against objects hurt it.
(You can't really see anything here or the pattern, but hey)
Your very flighty target. In my hometown, they're fluffier and lighter. Not sure what that is. (Also cursing my English. Nightactive = Moth? A moth is more than a nightactive butterfly, isn't it?)
(It's not that one but they're alike...)
Might be "Eisenfarbiger Samtfalter"
Still no idea about this dull, nightactive butterfly or moth