I may have missed how to organize or sort items on the quickbar (lots of times I recruit someone late-game and wish I could stick some spells on the Quickbar that aren't, or better yet extend the quickbar so I have quick access to more of the unit's spells). Regardless of whether or not it presently can be sorted, the automatic/default sorting produces inconsistent results.
I play Beastlord and love to Tame as many critters as I can, starting with web-capable spiders which really help me recruit others. Black Widows have two spells: Web and Beguile. Unfortunately, identical black widows have the arrangement of these two spells flipped on occasion:

Notice Web is in slot 1, Beguile in slot two.
With the Black Widow on the upper right, these are reversed:

This causes UI issues, as having a number of identical units and relying on a quickbar hotkey (like expecting 1 to be web) causes problems and can lead to the wrong spell being used, or players will have to slow down and check which, to me, is a mar against the intent of having quickbar hotkeys.