TEA implements slightly non-standart Save/Open dialog windows. They are big by default, and you can define their size at Preferences > Interface. The standart GTK+2 file chooser widget has no filename entry when it works in "File open"-mode. The TEA's dialog has it. There are two entries available: Directory and Filename. The Directory entry is used in the dual way. To navigate into the some directory, enter an URI, a full path or just directory name into this entry, and then press Enter or push the Go to button. To create a new directory IN THE CURRENT ONE, enter the directory name into the Directory entry and press the Create new button.
To save or open a file use the Filename entry - it works similar to the same thing in the KDE's file selector. Even the Enter key works! ;)