Scrollbar is visible in the type area (Win10)
And it scrolls the text by 1 pixel. The bug is there when the window is not extra small. In 4.8: Scrollbar seems to disappear when resizing a window but reappear whem selecting an other conversation In 5.0: Scrollbar is always there (except when the window is very small)

Could be because of my language and the tall "Í" character?
when i add "line-height: 1.29;" to ._kmc selector, it fixes the issue. And yes it's with my language as i see that this thing is causing the bug:

Same issue on my side.My language is Slovak
I hope i've fixed it here: https://github.com/Aluxian/Facebook-Messenger-Desktop/pull/460
@skyli91 can you open the issue on the official repo (aluxian one), because its difficult for me to maintain two repo :) Thanks keep up the good work
@skyli91 it also appeared on my system (french) with the latest beta. I might have to change the setting again... BTW https://github.com/Aluxian/Facebook-Messenger-Desktop/releases/tag/v1.5.0-beta.1