Normal/Titlebar border leaves trail

[acly7946]

See this video:

output.mp4

Sway Version:
sway version 1.5-64ea407f (Dec 14 2020, branch 'master')
(from sway-borders-git in aur)

Debug Log:
https://gist.github.com/acly7946/b35dd3ade136011b4bb8f37bf6d257a2

Configuration File:
default, with border images from contrib added

Description:
With 'normal' border aka titlebar enabled, moving a floating window will leave a trail of border image from the top.

• Does not occur with 'pixel' border
• Every application does this

[fluix-dev]

Just adding on, it seems there are even more issues when titlebars exist (there are transparent pixels after moving the floating window to another monitor).