Catching Mouse Clicks

["Koray Berk" <koray 2050 ws>]

Hi,
I have been developing software on Visual C++ for sometime now.
However finally I am diving into the Linux world (very recently, so I am
on the novice level with GTK).
 
I need a very simple jump start.
An application that draws a line between two points input by the user
via mouse clicks.  Or functions or widgets that will enable me to do
that.