If you see "abandoned libraries", you're probably looking at
DSource, which is dead. Everything has long since moved to GitHub.
Derelict provides good SDL2 as well as SFML2 bindings (and
bindings to many other APIs). For GUI, (assuming you don't want
Windows-only ones) TkD is simple and easy-to-use (think TkInter
in Python) although a bit new, GtkD is usable but not "perfect",
and there are many other frameworks/libs/bindings.
If you want very simple GUI in an OpenGL app, dimgui should work.
https://github.com/DerelictOrg
https://github.com/nomad-software/tkd
https://github.com/d-gamedev-team/dimgui
Also see the wiki (the old wiki is dead, just like DSource):
http://wiki.dlang.org/Libraries_and_Frameworks
And the DUB packages of libs and other projects:
http://code.dlang.org/
