gtk2-engines-pixbuf software package provides pixbuf-based theme for GTK+ 2.x, you can install in your Ubuntu 16.04 LTS (Xenial Xerus) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install gtk2-engines-pixbuf
gtk2-engines-pixbuf is installed in your system.
Make ensure the gtk2-engines-pixbuf package were installed using the commands given below,
$ sudo dpkg-query -l | grep gtk2-engines-pixbuf *
You will get with gtk2-engines-pixbuf package name, version, architecture and description in a table
| Distro | Ubuntu 16 04 lts xenial xerus |
| Section | Graphics |
| Package | gtk2-engines-pixbuf |
| Version | 2.24.30-1ubuntu1 |
| Description | pixbuf-based theme for GTK+ 2.x |
| Sub Section | Graphics |