You know, in beta they had a radial icon system for sending items to another player.
That's still in the game.
Personally I have yet to fill a single hotbar (for any character, including my mages) so I don't see the need. Will see if I do once I progress *much* further through the game.
I can approach 30 by end of first town.
Mage with schools of magic, potions and scrolls.
Ranger with specialized arrows, potions and scrolls.