[bug?] window decoration with "NewStyle = next;" appear sunken

Hi,

so I'm not sure if it qualifies as a bug, but window decorations appear
sunken when "NewStyle = next;", on preview image it doesn't seem to look
that way.
However I checked few older versions (0.95.5, 0.95.6, 0.95.7) and also
got 'sunken' look so not sure if it's a bug.

screenshot attached

Amadeusz