Distribution/Version: Ubuntu 5.10

1.) Mofify an existing drawing or make a new drawing
2.) Click "save" or "save as..."
3.) Type     mum with pink hair    as the name

Gimp doesn't want to save. It says the following instead:

unknown filetype, /home/... ... ..
saving failed.

This is, said mildly, unacceptable.

The new gnome save file dialog is so easy and clean that even nontechies feel
comfortable with it... until they click save.

You have to go back and write a "obscure" (for mums and little sisters) .bmp
.jpg ... suffix or open a treeview with lots of incomprehensible file formats
(again, mums and little sisters just fail to save and say "gimp sucks" unless
you quickly tell them that they have to put this misterious .png suffix)

How to fix, here my suggestion?

The warning if no fileformat is choosen is ok, but in my opinion the dialog
should be like this:

Button: "Save in the GIMP file format (for further modifications)"
Button: "Export as format:" <checkbox with, say, jpg as a default value>  Useful
for opening the image with programs other than GIMP

PS: Thank you for having improved the GIMP so much that even a 9-year-old can
use it for simple tasks.