Selecting launcher menu option "Quit" for GIMP only closes current item, not program

$ lsb_release -rd
Description: Ubuntu 12.10
Release: 12.10

$ apt-cache policy unity
unity:
  Installed: 6.12.0-0ubuntu0.2

When you have multiple files open in GIMP, right clicking on the launcher and selecting "Quit" does not work as expected.

Expected behaviour: GIMP shows dialog if there is unsaved changes in any opened items. When this dialog is dismissed, GIMP exits.

Actual behaviour: GIMP shows dialog if there is unsaved changes in the CURRENT item. When this dialog is dismissed, GIMP closes the current item. Once you have closed the last item via the "Quit" option (i.e. there is no items open anymore) clicking the "Quit" option again finally exits GIMP.

It seems like the "Quit" option is sending the equivalent of a <Ctrl>w to GIMP, rather than a <Ctrl>q. This behaviour is inconsistent compared to other applications. For example, selecting "Quit" for Firefox closes the application, rather than the currently open tab.

ProblemType: Bug
DistroRelease: Ubuntu 12.10
Package: unity 6.12.0-0ubuntu0.2
Uname: Linux 3.7.7-030707-generic x86_64
ApportVersion: 2.6.1-0ubuntu10
Architecture: amd64
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
Date: Tue Feb 12 16:49:15 2013
EcryptfsInUse: Yes
MarkForUpload: True
ProcEnviron:
 LANGUAGE=en_CA:en
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_CA.UTF-8
 SHELL=/bin/bash
SourcePackage: unity
UpgradeStatus: No upgrade log present (probably fresh install)