Do you mean slots that you can only pick up from, not place items in?
If so, you have to make a new class extending Slot. This tutorial puts it pretty well, in the section "forming a new GUI for this GoldFurnace", and even though it is for ModLoader, that part still works.
lol true, I do have to ask any mod that reads this: could you delete this post I have a updated tutorial on 1.3.2 on my forge 4.x tutorials tutorial... Thank you
thank you
Well not always, but it's a good place to start
Why would you want that? Forge is by far the best API for coding in things any more advanced than single blocks and such.
Ops, my bad! I ment, could you do one that only uses forge and not modloader? It is really confusing using modloader sometime! Thanks!