From LoTROInterface Wiki
Function to handle dropping any kind of item into the backpack. If the item is already in the backpack or is coming from a housing hook, it will perform a swap with anything at the destination index.
|function Backpack:PerformShortcutDrop(shortcut, destinationIndex, split);|
The LuaShortcut containing the item info needed for handling drag and drop. This MUST be generated by a valid drag and drop message or moving things from the vaults and housing hooks will generate errors!
The index into the backpack where you are trying to drop the item
Whether or not we want to split the item's stack while dragging it