The warning gutter icon appears as a black triangle in some color schemes (SL 3)

[mustafa0x]

For example, when using the Mac Classic theme:

I dug around a bit, and I think it has something to do with the scope argument of add_regions.

[jobedom]

You're right. I use a custom scheme with black keywords (very minimal theme) and also get black triangles.

I've fixed it for now changing the scope from "keyword" to "invalid". Maybe we could add a new scope definition to be used in color schemes, or pick another already existing scope.