First noticed in 1.291 the game I played on 1.29 did not do this and 1.20.

When clicking on something, it's acting as a double click, or multiple clicks. In combat if I go to cast a spell on myself (for example) it will cast then open the details window of my character. Once I close the window, it will then finish casting the spell. When leveling up, I clicked an ability (strength, wanted to see if it would be enough to boost initiative) and it acted as a double click selecting the ability.

Happens with hardware mouse checked or unchecked.