I will fix that when I compile version 1.44. I'm just waiting for the developer to officially release it.
In the meantime, feel free to fix your copy of the extension. It's an easy fix:
1. Copy the xfe.tcz extension from your tce/optional directory to any directory of your choice
2. Extract the extension like this:
unsquashfs xfe.tcz
This will produce squashfs-root directory
3. Put the icon you want in squashfs-root/usr/local/share/pixmaps/xfe.png
4. Put this line in squashfs-root/usr/local/share/applications/xfe.desktop:
X-FullPathIcon=/usr/local/share/pixmaps/xfe.png
5. Repack the extension:
mksquashfs squashfs-root/ xfe.tcz
6. Copy the new xfe.tcz to your tce/optional directory.
That's it.