This has already been discussed almost two years ago: http://lists.macromates.com/textmate/2014-October/037962.html

I just realized that since beta 9.3 it is possible to use coloured images for the gutter, so I decided to give it a try (see attached screenshot).

I like this look, especially as warning marks stand out much better now against the SCM status marks.

If you’re interested, here’s the fork: https://github.com/noniq/scm-diff-gutter.tmbundle/tree/coloured-marks

In the discussion back then Allan mentioned that he considered adding a dedicated “diff” api:

I like the mockup; but for the API, there are several parameters that set it apart from the single-color scalable shape one can currently place to the left of a line, so it would probably be better to make a dedicated “diff” API where the command set the status for a line range, and then it’s up to TextMate, how to visualize that.

Is this something that will be implemented in the foreseeable future? Or should I try to polish my current solution to make it ready for merging? (Open questions are at least: How to adapt for different gutter background colours? What about colour-blind people [1]?)

[1]: http://lists.macromates.com/textmate/2014-October/037980.html

Stefan