One way to use the change backdrop, show and hide blocks in conjunction to make a cool effect is to have a backdrop and a sprite on screen. Then, after a certain event, the sprite hides and the backdrop changes at the same time. This allows for a more realistic scene change. If you want to go back to the original scene, you can have an event that shows and changes the backdrop at the same time. Or while the sprite is hidden and you have the second backdrop, you can move the sprite off screen, show, and then step or glide on screen to make it seem like the sprite is moving from one backdrop to another.