(v24, linux)
When a character has a combat rigging perk, drag and drop between slots works sometimes differently than with two slots. Opening it as a bug, because how it shuffles isn't consistent (nor intuitive), but feel free to move. If may give a suggestion, would let the dragged item to be always dropped where was released, if possible.
Below are some observations how inventory operations behave, in case it helps anything.
Exchanging items between three populated slots:
-- from the 1st slot to the 2nd, instead of [1->2 2->1 3->3] the operation is [1->3 2->1 3->2].
-- from the 2nd slot to the 1st, instead of [1->2 2->1 3->3] the operation is [1->3 2->2 3->1].
-- between the 1st and 3rd slot (both ways), instead of [1->3 2->2 3->1] the operation is [1->3 2->1 3->2].
-- between 2nd and 3rd slot (both ways), the operation is [1->1 2->3 3->2], which seems to me all right.
There is some further variation with one hand empty. Eg. when the 3rd is empty, it exchanges items between 1st and 2nd slot normally, while when 1st is empty and you want exchange items between 2nd and 3rd, it shifts them into 1st and 2nd. Whereas when you have the 2nd empty and try move 3rd item to the 2nd slot, what it does is [1->3, 3->1], so not only shift but also shuffle.
When there are two hands empty: the 1st item can't be moved anywhere except to inventory, 3rd->1st also won't move, *yawn* 2nd->3rd goes to the 1st, whereas [NOW big bug warning!] both 2nd->1st as well as 3rd->1st operation will cause an item duplication! (not sure if duplicates are real as they sometimes disappear but was able to sell them). In case replication of this isn't clear, can supply step-by-step.
There are more combinations and inconsistencies with dragging items from inventory to weapon slots and back, think can also make different ghost items, perhaps even cause an item dis- and re-apperance... But it seems that all those peculiarities are often result of the shifting inconsistency, where an operation will sometimes shift items and sometimes it won't. Basically: if you have all hands empty it always puts the item to the first slot, no matter where dropped, the next one will end in the 2nd, etc.; whereas, when you remove an item from any slot, it doesn't shift the other items. -> This goes the same with only two slots, but with combat rigging it even more complexifies. Been thinking, is the slot shifting here meant as feature or is it perhaps like default inventory behaviour?