If you have a verb's argument require an item from a list, and the user double clicks an item in the selection prompt to select that item rather than single click + hitting submit, it will select that item, call the verb, then call the click event on the item under the mouse cursor.

(it might be calling the double click event for all i know, they tend to do the same thing)

This has caused issues with accidental discharge when the mob is holding a firearm.

This has existed in 507 and maybe even 506.