[Qt-interest] Force file extension with QFileDialog::getSaveFileName?

[David Doria]

>  It's a *HUGE* violation of Human Interface Design
>  Principles to do something like this. Reject an
>  extension/filetype if you don't like it, but don't
>  you dare change it behind the user's back to suit
>  your needs. That would certainly violate the principle
>  of "least surprise" and on some systems, might end up
>  with the user confused about why, having typed "foo.ppm",
>  the program is now asking them if they want to over-write
>  the exitsing "foo.bmp". (Or even worse yet, maybe the
>  program simply silently over-writes their existing .bmp
>  file with new contents; that loss-of-data accident could
>  spell a lawsuit!)
>
>                              Atlant

I agree with not changing the extension, but there should be a way
(the defaultSuffix sounds like it is on the right track...) to force
the result to have a .png unless they specified something else, right?
Like in many programs if you just type "test", it will automatically
append the extension so the result is test.png.