libxfce4ui-2-0 software package provides widget library for Xfce - Gtk+3 variant, 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 libxfce4ui-2-0
libxfce4ui-2-0 is installed in your system.
Make ensure the libxfce4ui-2-0 package were installed using the commands given below,
$ sudo dpkg-query -l | grep libxfce4ui-2-0 *
You will get with libxfce4ui-2-0 package name, version, architecture and description in a table
| Distro | Ubuntu 14 04 lts trusty tahr |
| Section | Libraries |
| Package | libxfce4ui-2-0 |
| Version | 4.11.1-2ubuntu1 |
| Description | widget library for Xfce - Gtk+3 variant |
| Sub Section | libs |