Sorry, I realized that the command reference is incomplete.
@menu menu.png menu-selected.png START 640 480 240 120
"640 480" locates the top-left position of the button on the screen. It's not center position, and it's not documented. I'll add some explanations to the command reference. Thank you for pointing out.
In this way, your feedback is important for this engine. So please feel free to contact me with any comments or questions.
Okay, I'll put it on my TODO list's top. Since this is my first time to edit videos, it will take several weeks.