$ sudo apt-get update
$ sudo apt-get install libqtgui4 

libqtgui4 is installed in your system.

Make ensure the libqtgui4 package were installed using the commands given below,

$ sudo dpkg-query -l | grep libqtgui4 *

You will get with libqtgui4 package name, version, architecture and description in a table

libqtgui4 package basic information: