Wrong image format in save dialogue

Reported via mail:

PreConditions:
-set Shutter to Browse for a save folder after each capture
-set jpeg as the image format

Bug:
On the screen "Choose a location to save to" after you take the
screenshot, the Image Format is still set to png. The file name has
the .jpeg extension so the following error is given after you click
Save.

"PNG compression level must be a value between 0 and 9, value '90' is
not allowed."

The "90" having been set from the jpeg quality slider.

Suggestions:
-If a different image format is selected as the default in the
Preferences menu, that the save screen use that format as well.
-You might even remove the image format from the Name as it really
isn't needed if you have it at the bottom of the screen. It would
allow the user to quickly select the whole field for changing without
having to worry about changing the format.