The QScroller doesn't work in a QStackedWidget with more than 1 widget that uses the QScroller::grabGesture(this, QScroller::LeftMouseButtonGesture);

Only the first widget that uses the scrolling will be able to use it, all the other widgets in the QStackedWidget will not. When two QStackedWidgets are stacked on each other, only 1 widget in 1  QStackedwidget  will work and none of the others. 

I attached a simple program that has 4 widgets, all using the QScroller of which
2 are in a QStackedWidget,  only 1 of the 2 widgets in the QStackedWidget will work.