1. Add capability support for Quark's TileEntity/ItemStack APIs. Mostly thinking of IDropoffManager here.
2. Speaking of IDropoffManager, is it possible to add a default method which lets me give it a custom IItemHandler?

2 is acknowledged and will be in the next release. I'll leave 1 for later.

Okay! I was thinking of adding dropoff support to my barrels, that's why I was asking. (Would it be a good idea?)

Knock yourself out. I just won't do 1 right now because I don't have a lot of time on my hands to learn the capability system too well. If you want to PR it that would be appreciated.

Don't have much time myself (January is the month of incoming finals over here), sorry! But hey, at least it's acknowledged.

How's this?

Nevermind, that only does it for one case. Give me a sec >_>

@Vazkii That's terrible.

Say, SlotItemHandler. The inventory won't help much here. Make two methods - one passes the TileEntity (for the other case), the other passes... something else. The container the player has open, maybe? The slot?

Ok I think this one should work well enough?

Yes, except I'd still add separate support for SlotItemHandlers over just checking slot.inventory (or, better yet, allow implementing IDropoffManager on the Container object itself?). Other than that, though, this should be good, and is definitely good enough for what I had in mind!

Though I do still depend on #736 ...