How do I limit the number of dropped items for a box?

[cuadernos]

I am just learning jquery, so this might be something easy.I am trying to make a really basic game that you can drop the name of the color onto the color box (to help learn about droppable and draggable).I got it working except a few problems.[*]How do I limit the number of items to 1? (Is there a way to check if something is "dropped" onto the box?)[*]How do I send the data to a php script?Here is my demo (removed)Thanks for your help.========Ok, I can disable the drop boxes after you drop in into a box. But, if you decided to change you mind I need a reset.demo2How do I reset the color names back to the original location?