As of January 11, 2019, gtkDcoding is up. It's a blog, it's a github page, it's simple examples of how to use GtkD for all that GUI stuff.
My approach is to lay out a firm foundation for both imperative and object-oriented paradigms, then build from there, taking things one step at a time.
This being Friday, the 4th post went up this morning. Please do let me know if you find it useful.