I was working with the graph groups and wanted drag and drop ability or for paths defined to use the more specific path before using a parent path for color selection.
I did not know that drag and drop was available until I read this forum post: Re-order groups after creation
A drag indicator/handle would indicate to the user that drag is available.
2 such icons: Google Fonts
Right now, the tooltip on the color selector button says you can drag to reorder the groups. It’s not visible unless I’m looking at tooltips.