function showDialog(vis){
if(vis == "block"){
//document.body.scroll= "no";
document.body.style.overflow="hidden"
}else{
//document.body.scroll= "yes";
document.body.style.overflow=""
}

// Retrieve width and height of client browser.
var cw = document.body.clientWidth;
var ch = document.body.clientHeight;

// Disable background
var bg = document.getElementById("bgDisable");
bg.style.width = cw;
bg.style.height = ch;
bg.style.display = vis;

//Show dialog at the center of screen.
dialog.style.top = (ch - dialog.style.height.replace(/px/,""))/2;
dialog.style.left = (cw - dialog.style.width.replace(/px/,""))/2;
dialog.style.display = vis;
}