This is an advanced project that demonstrates how to make a scrolling background.
simple loops, visibility, delays, simple sound playing, direction and turning, simple events, detect conditions, advanced events, simple motion, simple costume handling, advanced costume handling, screen bounds, functions, advanced motion, basic math, actor properties, advanced messaging, miscellaneous, simple conditionals, graphic effects, simple messaging, text handling, layers, expert physics, simple variables, variables, input/output,