From squeek502/AppleSkin#6

I haven't looked at the NEI code, but I would assume it's because NEI isn't providing the ItemStack when they do their tooltip rendering or has custom tooltip rendering code that bypasses the Forge event that AppleSkin relies on.

See mezz/JustEnoughItems#388 and mezz/JustEnoughItems@311c538 for when JEI added support for the relevant Forge event.

AppleSkin listens for RenderTooltipEvent.PostText and expects the event's ItemStack field to be non-null.

Ahh, ill quickly add that.

Now working as expected \o/ http://ss.podgeweb.com/85b8tfe.png
Commit will follow shortly.