Is there a way to save an edited, pre-existing color ramp as a new color ramp, or export the edited color ramp in QGIS 2.18.xx?
I'm able to take an existing gradient ramp, say, "Blues", and edit it, which is very handy. After editing the name of the ramp changes to "[source]":
…and the layer is styled with the edited ramp– however, the actual edited ramp itself doesn't seem to persist when I save my project file, save the style, etc… the layer itself remains styled in that edited color ramp, however. If I want to edit the ramp further or transfer that ramp to a different layer, I have to start from scratch:
When I launch the layer properties dialog again, the ramp comes up blank, and I'm unable to edit it: 
Right now my workaround is to write down all of the information for the edited ramp (values, percentages, stops, etc…) and create a new ramp from that… but that's rather inefficient. Just want to make sure there isn't something obvious I'm missing before I submit a bug report / feature request.
Best Answer
Looks like you can do it in QGIS 3 (2.99). I'm not sure if that means you shouldn't submit a missing feature for 2.18. -Bas