To avoid conflicts with normal ids, it seems we want to choose large numbers for altIDs. Testing this out: Create a new stack. Create one button. In the message box, "set the altID of btn 1 to 888888888" In the message box, "put the altID of btn 1" Result: 24120 Tried this again, using 999999999. Result was 51711 What's going on? Many thanks. David Epstein