The following window (and its contents, should it have any) is the correct size with 5.10 and v5.11.0, but with the latest 5.11 the device pixel ratio (2) is ignored and it is half the size it should be:
int main(int argc, char *argv)
QGuiApplication app(argc, argv);
import QtQuick 2.8
import QtQuick.Window 2.2
This happens when running the application from Creator or on the command line.