I believe most users expect to be able to search the file/directory table by
entering the beginning of a file/folder name without having to press ctrl-f
first to enter "search mode". (The key combo isn't obvious to the average user,
and not well advertised either.)

The same goes for having to press ctrl-l to enter "keyboard navigation mode",
see bug 136541.

I think these changes would improve HIG compliance and general usability for all
users (average users, power users, disabled users) of the new file chooser.

As these things were possible in the old chooser (the text field where it was
possible to enter and complete filenames made it possible) and as the file
chooser is such a high profile dialog, I think it should be considered a high
priority to restore this important(!) functionality.

(Severity chosen according to "severity and priority guidelines" - difficult to
use, high visibility regression.)