To use this plugin you will need to build the provided
helper C program, see below.

To install the plugin, as usually, copy this directory
under the Tkabber's plugins directory ~/.tkabber/plugins
so that you get a hierarchy like this:
  ~/.tkabber/plugins
  ~/.tkabber/plugins/urgent/
  ~/.tkabber/plugins/urgent/urgent.tcl

Ensure you have a C compiler and X11 development files installed
("gcc" and "libx11-dev" packages on Debian systems),
then change to the plugin's directory:
$ cd ~/.tkabber/plugins/urgent/
and build the helper C program:
$ gcc -lX11 -o urgent -urgent.c

On older systems you might need to add an appropriate library
path to the gcc's search path using the -L command line
parameter, something like
$ gcc -L/usr/X11R6/lib -lX11 -o urgent -urgent.c

Restart Tkabber, to get the plugin loaded.
Visit the Cutsomize->Plugins->Urgent group of settings.
Consult the README file for the details about using this plugin.