So that would be an extension for MPTM format (since you somehow need to retain the markings across sessions)?

Yup, pretty much.

I guess this is pretty much similar to the pattern annotation feature request?

Yes and no. I prefer to be able to glance the orderlist and immediately see which pattern I coloured. I prefer not to click every pattern in the orderlist to find my annotation. But I guess they could be combined, as in that the annotation could have a colour attached to it, and you would see that in the orderlist itself.

The latter was exactly what I had in mind. There is no need to turn this into two distinct features.

Yeah, I'm totally fine with that. :)

+1

I could definitely use this. Both the quick coloring and the annotations. ;)

As of r24105, it is now possible to assign colors to patterns in the Pattern Properties dialog. While the assignment is always possible, the colors are only saved in MPTM files. I first wanted to have them in XM/IT as well, like channel colors, but this would have complicated the feature quite a bit for technical reasons, so it wasn't worth it.

Right now the color is shown as a strip at the top of the order list, similar to the channel colors. There's probably room for improvement, though, so if you have any better idea, do speak up.