shouldn't save without file extension

[[mrs_sheep]]

Reproduce:
Run gnome-screensaver or press [PrtSc]. Change the name of the file to save to 'Test' and save.
You now have a file "~/Test".

Issue: I had to send this file to a Windows user who couldn't open it, because the file extension was missing. Not a big deal for me, but I think a not tech-savvy person would have a hard time understanding that they have to add ".PNG" to the file name.

I propose that the gnome-screensaver should add the file extension automatically.
If this is against some guide-line there should be some kind of alert.

[I know that by default only the not-file-extension part of the file name is selected, so if you would type right away there would be no issue. But users don't always behave that way.]

ProblemType: Bug
DistroRelease: Ubuntu 13.04
Package: gnome-screenshot 3.6.1-0ubuntu2
ProcVersionSignature: Ubuntu 3.8.0-26.38-generic 3.8.13.2
Uname: Linux 3.8.0-26-generic x86_64
ApportVersion: 2.9.2-0ubuntu8.1
Architecture: amd64
Date: Fri Jul 12 14:50:56 2013
ExecutablePath: /usr/bin/gnome-screenshot
InstallationDate: Installed on 2013-02-14 (147 days ago)
InstallationMedia: Ubuntu 12.10 "Quantal Quetzal" - Release amd64 (20121017.5)
MarkForUpload: True
ProcEnviron:
 SHELL=/bin/bash
 XDG_RUNTIME_DIR=<set>
 PATH=(custom, no user)
 LANG=en_US.UTF-8
SourcePackage: gnome-screenshot
UpgradeStatus: Upgraded to raring on 2013-04-25 (78 days ago)

[Graham Inggs (ginggs)]

Although it does not prevent one from saving a file without an extension, LP: #1169904 should alleviate the problem by allowing one to type the filename without losing the extension.

Marking as a duplicate. Feel free to unmark as a duplicate if you feel this does not apply.

[[mrs_sheep] (mrs-sheep)]

I would like to unmark it, because you can actually start writing right away by now [13.04] (see in my bug report).
My bug is against the case when you (accidently) delete the file extension.