reference to drawn objects

[Steven De Groote <stevendegroote f1technical net>]

hi,

I am a student in computer science and I'm currently working on a 
project that involves graph drawing.
As some of you are probably quite experienced with drawing software I 
would like to know how you keep track of objects that are drawn on the 
canvas.

I am drawing several things such as splines, however as the user clicks 
I must be able to know which object he marked, but I'm stuck there..
Do you have any advice on how to keep track what object is where? How is 
that done in DIA?

Regards,
Steven