Applications menu does not resize xpm icons

[pqwoerituytrueiwoq]

As you can see supertuxkart uses a large xpm icon and the screenshot shows it not being scalled down to fit in hte menu icons alloted space

~$ cat /usr/share/applications/supertuxkart.desktop | grep Icon
Icon=/usr/share/pixmaps/supertuxkart_64.xpm

Workaround:
sudo sed -i 's/supertuxkart_64.xpm/supertuxkart.png/' /usr/share/applications/supertuxkart.desktop
this changes the icon in the .desktop file to a png file

ProblemType: Bug
DistroRelease: Ubuntu 13.04
Package: xfce4-panel 4.10.0-1ubuntu2
ProcVersionSignature: Ubuntu 3.8.0-7.14-generic 3.8.0
Uname: Linux 3.8.0-7-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.8-0ubuntu4
Architecture: amd64
Date: Thu Feb 21 11:56:43 2013
InstallationDate: Installed on 2013-02-21 (0 days ago)
InstallationMedia: Xubuntu 13.04 "Raring Ringtail" - Alpha amd64 (20130220)
MarkForUpload: True
SourcePackage: xfce4-panel
UpgradeStatus: No upgrade log present (probably fresh install)