On 25 May 2016, at 8:42, Jacob Carlborg wrote:
I don't think ICNS is a requirement. The built-in icons, error and warning, use PDF, IIRC.
Correct, they can be any format that is supported by NSImage (TIFF, GIF, PNG, etc.).
We use PDF for the current gutter images because that allows us to use vector images.
[…] If one runs a build command for Sass or LESS which use marks to report errors they would override the colors.
The images are “stacked” although only top one is drawn. But that means once the issue is fixed, the warning/error image should disappear and again reveal the color.