Triggers on a submit button for drag and drop

Start with the Submit button in Hidden state

Create the trigger:

Change state of Submit to Normal When Object 1 is dropped on [any of the targets] if Object 2 is Drop 
Correct Or Object 2 is Drop Incorrect And Object 3 is Drop Correct OR Object 3 is Drop Incorrect And etc.

You will need one of these triggers for when each object is dropped.

I think this will work, but I’m not currently with SL to test it. It depends on how it combines the Ors and Ands. If it bunches the ORs, then The ANDS, it will work. If it just runs through linearly, it probably won’t. In that case, you will have to create the checking one step at a time. Unfortunately, SL doesn’t have a Dropped state at this time, so you will need a variable for each object to show if it is either Dropped Correct or Drop Incorrect. Then each time an object is dropped, check the other objects to find their state and set their variable, then another trigger to show Submit if all the variables are True.