blackbird-gtk-theme software package provides dark GTK+ theme from the Shimmer Project, you can install in your Ubuntu 17.04 (Zesty Zapus) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install blackbird-gtk-theme
blackbird-gtk-theme is installed in your system.
Make ensure the blackbird-gtk-theme package were installed using the commands given below,
$ sudo dpkg-query -l | grep blackbird-gtk-theme *
You will get with blackbird-gtk-theme package name, version, architecture and description in a table
| Distro | Ubuntu 17 |
| Section | X Window System software |
| Package | blackbird-gtk-theme |
| Version | 0.4+20160704~ab4a30e-1 |
| Description | dark GTK+ theme from the Shimmer Project |
| Sub Section | x11 |