Scrolling would help, there are many people who share scrolling screen code. Just put a question to the discussion board and several people will jump in.

You could make a variant of this puzzle that could be pretty cool, use Tetris like pieces and pull them out , when a person grabs a piece they might have to rotate it to fit. and then to make a level a bit harder throw a piece in the bucket that they do not need or simply cannot use.

I do not have the sound on, I would have expected it to be on the last bag, or better yet - have it so when the last bag is picked up you have to catch a get away car to win.

It would be cool to see what would happen if you could make an unexpected light change - like clicking on the traffic light to change it - or what if a car does not obey the traffic light, or pulls a jerk move?