How to expand elements in `freesimpleguiqt`

Hi,

I'm using `FreeSimpleGUIQt` for my project. I would like to expand some elements to fill the width of the window. In "plain" freesimplegui I would use `expand_x = True` in the arguments, but `FreeSimpleGUIQt` doesn't support that.

What is the correct way to expand elements, assuming there is one?

Thanks!