I would be inclined to not use QFileDialog for that task -- it's designed to look and function the way users expect a file selection dialog to work, which includes navigation. I have a similar use-case in a program I'm currently working on, and my solution was to create a very simple custom dialog that simply presents a list of the files they are allowed to select from. It's very easy to get that list from a QDir and drop that QStringList into a QListWidget.

@SGaist Thank you once again!
Now, I can manage to display the folder list inside the stacked widget page using QTreeView + QFileSystemModel combo!

@Jeroentjehome
Thanks for the reply. It fixes the problem, for sure.
But in the other hand such feature would be very useful.
I will create a feature request and post it here later, if somebody else is also interested.