Screenshot in indexed color palette (or how to post a feature request)

Hi,

I'd like to suggest a new feature...
Given the fact that the Blueprints area is disabled and that the Github project has issues disabled as well, I'm down to asking it as a question... where do I suggest new features?

Many times, I end up reducing the color palette of the screenshots I've taken by opening them in Gimp, going to Image -> Mode -> Indexed colors. This saves roughly 5 to 10 times the volume of the file, and most often it doesn't degrade the screenshot much.
As such, I think it would be great, in the popup window allowing you to select the screenshot mode, to offer an option to immediately use a 255 colors palette. This would save hundreds of GB worldwide and reduce the carbon footprint of gnome-screenshot by using less hard drives :-p