How do I Make (Fullscreen: Off) be centralized?

There is anyway I can get to make the option (Fullscreen: Off) be centralized? I Don't think this is what I am looking for, but I think if this have a solution I might get what I need...

I don't think so.

Using "Fullscreen: Off" option is a bad idea, I suggest studying this tutorial:

construct.net/en/tutorials/supporting-multiple-screen-77

In javascript if you can access the canvas element you can center it with some css:

canvas.style.position="fixed";
canvas.style.left = Math.max(0,(window.innerWidth -canvas.width )/2)+"px";
canvas.style.top = Math.max(0,(window.innerHeight-canvas.height)/2)+"px";

Thx I'll try this soon.