Fullscreen Toggle Button Action Script 2.0 : Flash

Add Action Script in Flash 

btn = "Button Instance Name"

Flash Action Script

stop();
Stage.displayState = "normal";
Stage.scaleMode = "noScale";
function toggleFullScreen ()
{
    trace ("::::::::::::::::::::::::::::::::::::::::");
    if (Stage.displayState == "normal")
    {
        Stage.displayState = "fullScreen";
    }
    else
    {
        Stage.displayState = "normal";
    }// end else if
}
btn.onRelease=function()
{
toggleFullScreen () 
}

HTML  Code : Replace your Swf file path with "index.swf"