Clicking the scroll bar causes that the drop-down list won't hide when you click outside the drop-down menu.
Steps to reproduce:
The same bug won't reproduce if you scroll the drop-down list by using the mouse wheel.

I had the same issue. I am still looking for a way to fix it. Please answer if you figure out. Thanks.
Waitting...
When will this fix be deployed?
Fixed and deployed in v2.6.2. Thanks for the detailed issue @juhoheinonen, and thanks to @hrobertson for a couple great PRs.
@tranvanba1992 FYI your comment is not appreciated or helpful.