No problem. Do bear in mind that if you decide to send the event with QApplication::sendEvent, you are responsible for the event object's deletion, so it's a good idea to create it on the stack in that case. Good luck!
I found out the solution using native Windows Gestures WM_Gesture.
By default QT registers QMainWindow-Window as a Touch Window, so the QMainWindow-App only get WM_Touch events.
As said above one can only get either WM_Touch event or WM_Gesture event. So you have to unregister the window from getting Touch event. I do that in the constructor like this:
Sounds like you may have found a regression. You should take a look at the bug report system to see if it's something known. If not please consider opening a new report providing a minimal compilable example showing the behavior