Bug fix for Projectile Motion 1.  The Left Click and Enter weren't being consistently cleared, and so the simulation would skip step 3.

But including these lines in the create event solves this:

mouse_clear(mb_any);

keyboard_clear(vk_enter);

I also solved an issue where the button to open the Desmos Graphing Calculator didn't open in a new tab, but changed the old tab.

This was needed:

url_open_ext("https://www.desmos.com/calculator","_blank");