IMHO the new File Selector Widget should:

a) have advanced features for creating, renaming and removing files and directories;
b) have a left panel like the KDE's one, with customizable most-used entries (home, temp, docs, floppy, cdrom, cdwriter, etc.);
c) have, in Save mode, a box for entering a password/passphrase for encryption needs;
d) have a Filter combo-box with entries corresponding to MIME-types;

thanks :)