You may have heard the rumour that GTK/GNOME developers make software for simpleton users that don't exist. But you've just run into a power user feature that you don't understand.

Now, what do you think will happen if the GTK/GNOME developers get rid of that "bizarre textbox" so it doesn't get in your way? Yes, they'll get a torrent of abuse for "removing the last power user feature" or something. :-)