Installer issues on Linux

These are various issues I've encountered while testing an IzPack installer on Linux (specifically Ubuntu/Gnome). I installed this as a non-root user.

a) creation of 'main menu' subgroups doesn't work

If I e.g. specify the $APP_NAME as the program group, no shortcut is created at all. If I however install again, a shortcut in the group "Other" is created

After that I specified the programGroup Accessories. I.e.
<programGroup defaultName="Accessories"
location="applications"/>
This works on 1st installation. However:

b) On repeated installation an (additional) shortcut in the program group "Other" is created
For every following installation an additional shortcut is created in this group

c) Consequently these additional shortcuts are not removed, when I run the uninstaller

d) Categories don't have any effect?
I didn't quite understand from the documentation what categories are good for. However, they don't seem to have any effect. I've specified the category
Categories="Utility"
but he 'Categories' key in the .desktop file (of which BTW a new one is created for each installation) under ~/.local/share/applications is empty

e) Desktop icons on Gnome don't work
Okay, that one is already mentioned in the documentation