I've included a short sample program to demonstrate this problem.

qmake, make, then run the program.

The program creates a QSplitter in a QDockWidget. The top part of the splitter contains 4 QPushButtons; the bottom contains a QQuickView loaded using QWidget::createWindowContainer.

The problem is easy to see – it is impossible to click on the top-most button (actually, the very bottom few pixels of the button work, but not the top portion of the button).

Having the QQuickView in the splitter seems to block mouse clicks to the top 32 pixels of the splitter.