Holding left click down (moving) left click will start dialog or go through a portal or open a shop window etc. Basically itll act like you single left clicked the person/shop/portal.
Shouldnt be able to interact while holding down the movement mouse button.
I seen a post but it was locked so starting a new thread.
This is a known issue… its mainly a problem for inadvertently activating a portal before you are ready (like picking up loot first)… The devs know about it but they have not provided any specific details on correcting the issue yet.