It would be nice to have a file/folder picker control, similar to the DatePicker - a textbox and a button that shows a popup to help you locate the file.
But the official guideline does not provide a design guide for FileDialogs.
Most likely because mobile devices have their own file picker, provided by the OS instead of the app.
I'd like a file/folder picker "view" similar to this:

The pic above is file manager but I'd like something similar to pick files/folders. Ability show meta data in order to help pick the right file. Should be possible to host in a dialog or a plain view.
Might be too big for MDT and could possibly be a separate library with styles for both MDT and MahApps.
@Tyrrrz I might need such kind of controls in the near future, so I started them here.
Most helpful comment
@Tyrrrz I might need such kind of controls in the near future, so I started them here.