Comment 4 for bug 704265

I think this is the same but as https://bugs.launchpad.net/pinta/+bug/702029 the problem is not with upper/lowwer letters of jpg/JPG but with File | Save as.

Try this:
1. Run Pinta
2. You can do some drawing if you like, but I didn't I just selected File | Save as
3. Save Image File window opens, you can name the file as ever you like (with upper or lower letters), I have done the following: picture.jpg

But look into the File type you will see file type is selected (it depends on what was the last file type you have used, because it remembers file type). So far no problem.
4. Now you can do some additional drawing if you like, but I didn't I just selected File | Save as AGAIN (first time was at step 2). Name the file what ever you like, but please look at file type drop-down window - it becomes blank! So if you click on Save button you will get an error. But if you select some file type like jpg everything should be working fine.

I think that Pinta should ALWAYS remember the last file type that was used to save a file. If the file was never saved before it should use one of the file types like PNG. In my humble opinion Pinta should NEVER left file type drop-down list empty.