i3, also keep mpv on ws 9.

files/settings/i3.config

@@ -263,6 +263,7 @@ assign [class="(?i).*transmission.*"] $ws7
 assign [class="(?i).*rhythmbox.*"] $ws8
 
 assign [class="(?i).*vlc.*"] $ws9
+assign [class="(?i).*mpv.*"] $ws9
 
 assign [class="(?i).*vpn.*"] $ws10
 assign [class="(?i).*mullvad.*"] $ws10