Spot the difference - using collisions

[funksallbrother]

HI everyone.

I'm just making a fun 'Spot the Difference' game in Flash MX and have managed to make some clickable crosshairs on the page so that you can highlight the differences between the two pictures.

What I want to do next is make invisible areas on the 'spot the difference' picture so that when the user clicks 'submit answer' to see if they have spotted all the differences. The script checks the page and sees whether all crosshairs are lying on the invisible areas. If they have found the differences correctly it will take them to a Winner page and if they haven't it will take them to a page saying 'try again'.

Has anyone got any ideas or places where I could go for tutorials on this matter?

Thanks in advance,

Funksallbrother