Folder Manager is messed up in apps very annoying.

[az2020]

Install dconf editor - launch it then click the search button. Type 'directories' - you're looking for org.gtk.Settings.FileChooser sort-directories-first

Click the slider to set that to True.

That will list folders before files in gtk apps

Thanks for posting that. I struggle with these app-specific file choosers. Your tweak fixes half of what I struggle with (directories mingled with files). IMO: this option (directories first) should be the distro's default.

These file choosers still bother me the way they show tiny thumbnails (they only show a large preview when you highlight a file). You wouldn't have a trick up your sleeve for that one, would you?