Unlimited canvas painting program

[markotaht at gmail.com]

So, i`ll take the canvas, somekind of mouse tracker, for each mouse location il draw a dot or 2X2 square or something. Main thing i have never understood, is how can i get the backround to move. 

Lets say ia hve 200X200 window. In the middle of it is the cursor that draws. If i move the mouse the cursor doesent move, but the canvas moves. So if i move mouse to the left, i get a line that goes to the left. So i probably must invert the canvas movement. If mouse goes left, canvas goes right. 

And if possible i would like to save my piece of art aswell :D