Your logic seems to be correct.
What you have to do is to move the re-calculation of Scrollbar size & position to the Rectangle rcPageContainer because you are applying scale for that.
@jpnurmi Thanks for the clarification!
Looks like you are trying to use a Ui_otherPage without setting it up.
Why not use the widget you created with it ?
My first thought is that QGroupBox probably provides a sizehint() that is zero if the widget is not visible where your other widget probably does not do this.
The QStackedWidget would provide a sizehint() based on all of the children. When you hide the children you make the end result no smaller than the largest child.
Another idea to implement this is to have a common set of options always visible and show/hide the additional parts that are unique to the 'multi' and 'other' views. This will autosize.
Sure you can. One thing that you might use is a QProgressBar (with min and max at the same value so it's animated as in don't know how long it can take. Or you can use a gif in a QMovie object.