I have two question and thought it would be better if I ask them in the same thread, hope it's ok!

1. Font scaling with resolution
Is it possible to assign different font size depending of the screen resolution? (not when resizing window)
I was thinking of detecting the screen size when launching the application and then attributing a correct font size depending of the resolution. But I'm afraid this will mess with the layouts and other elements, like the font overflowing neighboring elements, or words being cut in half...
I use a fairly large screen myself, but some of my users use really giant screens and the fonts are quite tiny.

2. Custom layout for QFileDialog
Is it possible to just change the position of certain elements in the QFileDialog?
I'm in Linux and I want the "Open" button on the bottom right and the file extension on top.