this is how to make a thumbnail for your professional projects
1: make your thumbnail and go to code

2: put this code into the thumbnail

when green flag clicked
set [ghost v] effect to (100)

3. at another corner put this script WITHOUT a green flag:

show
go to front
go to x: (0) y: (0)

4: click on the script WITHOUT the “when green flag clicked” block

5. don't do anything and press see project page
6. press the green flag
7. press the stop button
8. if the project did not have a thumbnail, restart or look at the code