I'm just starting writing a GTK app, and on Windows the window decoration looks shit. It's the wrong font, the wrong icons, the wrong corner rounding, etc. MyPaint does it perfectly though! How? I've grepped the code a bit and couldn't find anything.
Here's a SO question of other people failing to do the same (and it shows how shit it looks by default): https://stackoverflow.com/questions/37035936/how-to-get-native-windows-decorations-on-gtk3-on-windows-7-and-msys2