I have enabled icons in menus, and most of them show up well (folder icons, file icons, save icons, etc.). But whenever an app tries to use an icon specific to itself, such as GIMP, it replaces that icon with the app icon, so that when I look at a menu in GIMP, I see most of the time just icons of GIMP's logo (that seems to be the only problem; the text is fine). I thought this was proper to GIMP, but I also noticed it happening on AbiWord.

Thankfully, as I said, it's not for all icons. But it still bugs me. Why is it so?

Here is a screenshot of a menu in GIMP:

I am using Ubuntu 11.04 Natty Narwhal, with Unity desktop (the problem also occurs on the Classic desktop, if I remember correctly).

EDIT: This does NOT occur on the Classic desktop; only in Unity.