This block would be yet another useful thing for online games, or responsive games. Let's say I'm in an online game. What if I want an element that shows the amount of players online? I would add a number to a counter when the flag is clicked right? What about when the person closes the game? This is where a ‘when stop clicked’ would be useful.

when 'stopsign' clicked :: events hat

It would also be cool if a game could say goodbye when you clicked the stopsign

This is a rejected suggestion.

LionHeart70 wrote:

23: When stop sign clicked:
The stop sign is designed to stop all scripts in the project, and having more scripts start when the project is stopped could defeat the purpose of that. It potentially could be confusing for the “stop all” block as well.

And it’s also something that can be implemented with the current Scratch blocks. The “When timer >” hat can be used to run a stack after the stop button has been clicked. A lot of people do this to display a thumbnail after someone uses the stop button. Here’s a program that can’t be stopped. https://scratch.mit.edu/projects/228668729/

Actually, I wish that the explanation in the sticky would explain it this way since it would be better to encourage people to try things out and learn things. It’s better, I think, to say that the stop button just stops the currently running stacks and that the ST resists adding a new block if there is the possibility that most people will figure out another way to do it with the exiting blocks (according to the Scratch design principles).