Qt is not true Cocoa, even still - IIRC (and I think it was literally somewhere on this forum that I was corrected by a Qt engineer) they use the Cocoa things t

Qt is not true Cocoa, even still - IIRC (and I think it was literally somewhere on this forum that I was corrected by a Qt engineer) they use the Cocoa things to handle some drawing code, but it's still their own stuff on top of that (they used to use HITheme & co before they modernized it). It's why you'll see subtle differences on things like buttons.