[Feature request] (Re)implement Mint-X dark/mixed themes #541

Currently only the Light variant of Mint-X is selectable...

but Terminal shows that it has a Dark theme variant as well:

It would be both pretty nice to have a Dark and/or Mixed variant selectable in the Theme preferences, with the Mixed theme having a dark panel and dark Cinnamon-specific elements and, optionally, a dark titlebar/menubar (and toolbars + CSD whenever possible) as a throwback to the older versions of the Mint-X theme:

If I knew how to make/edit GTK2/3 themes I would, but I don't, so for the time being asking is the best thing I could've thought of.