diff --git a/polybar/config.ini b/polybar/config.ini
index d726f81..e663541 100644
--- a/polybar/config.ini
+++ b/polybar/config.ini
@@ -397,6 +397,8 @@ tail = true
 
 [settings]
 screenchange-reload = true
+; they say: see https://www.cairographics.org/manual/cairo-cairo-t.html#cairo-operator-t
+; but I have no idea what this is supposed to do
 ;compositing-background = xor
 ;compositing-background = screen
 ;compositing-foreground = source