Add result on click instead of mouseup

This is a fix for #1386.

When starting a scroll with a Wacom pen I have to press a secondary button and then drag the list, this doesn't trigger a `mousedown` event. But when I release to extend my scroll, the `mouseup` event is triggered, and thus the list is closed. Changing the result adding on click fixes this as a `click` event is only triggered when there has been a `mousedown` and `mouseup` event.