Hello Erik.
If it's the sidebar in Finder windows (where you can keep your favourite folders) that you're missing in the Scribus file dialog then I've just today reported this as an issue in Mantis
http://bugs.scribus.net/view.php?id=11170The dialog currently allows you to drag folders to the "sidebar" but it doesn't keep the list between operations (it just forgets what you've dragged there the next time you open it). So it has partial functionality but it's not quite useful enough to be a real time-saver.
Maybe this is just a feature I don't know how to use properly but it doesn't seem right to me, and I couldn't find anything in the preferences, help or wiki. Maybe I'm just not doing things right?
I have no idea if this is an issue in any other operating systems as I only use Scribus on OSX.
I'm hoping that this will just be a simple "click here and here and it's fixed" type of thing. Scribus has so much functionality it's sometimes easy to get lost in it all, especially when you don't use it every day.
Garry.