add handle to image Box

i am trying to make it so that after a user clicks a button, every time he clicks on an image box, a point is drawn there. when he clicks the button again, this functionality is removed.
i am thinking of doing this by adding a click handle to the image Box, but i don't know how to do this...
any ideas?
i know i could just use a check box and an if(box.checked)... statement, but that seems kind of stupid and and unprofessional.


thanks...

What about having boolean variable that changes after each click .

VB Code:

If b =true then 
do this 'it means you set b = false
else
do that 'which means you set b =true 
end if

I might got you wrong though .