gtk-theme-config software package provides simple interface to change GTK+ themes, you can install in your Ubuntu 14.04 LTS (Trusty Tahr) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install gtk-theme-config
gtk-theme-config is installed in your system.
Make ensure the gtk-theme-config package were installed using the commands given below,
$ sudo dpkg-query -l | grep gtk-theme-config *
You will get with gtk-theme-config package name, version, architecture and description in a table
| Distro | Ubuntu 14 04 lts trusty tahr |
| Section | GNOME |
| Package | gtk-theme-config |
| Version | 1.0-1 |
| Description | simple interface to change GTK+ themes |
| Sub Section | GNOME |