function getPageSize(){
var xScroll, yScroll;

if (window.innerHeight && window.scrollMaxY) {
xScroll = document.body.scrollWidth;
yScroll = window.innerHeight + window.scrollMaxY;
} else if (document.body.scrollHeight > document.body.offsetHeight){ // all but Explorer Mac
xScroll = document.body.scrollWidth;
yScroll = document.body.scrollHeight;
} else { // Explorer Mac...would also work in Explorer 6 Strict, Mozilla and Safari
xScroll = document.body.offsetWidth;
yScroll = document.body.offsetHeight;
}

var windowWidth, windowHeight;
if (self.innerHeight) {// all except Explorer
windowWidth = self.innerWidth;
windowHeight = self.innerHeight;
} else if (document.documentElement && document.documentElement.clientHeight) { // Explorer 6 Strict Mode
windowWidth = document.documentElement.clientWidth;
windowHeight = document.documentElement.clientHeight;
} else if (document.body) { // other Explorers
windowWidth = document.body.clientWidth;
windowHeight = document.body.clientHeight;
}

// for small pages with total height less then height of the viewport
if(yScroll < windowHeight){
pageHeight = windowHeight;
} else { 
pageHeight = yScroll;
}

// for small pages with total width less then width of the viewport
if(xScroll < windowWidth){
pageWidth = windowWidth;
} else {
pageWidth = xScroll;
}


arrayPageSize = new Array(pageWidth,pageHeight,windowWidth,windowHeight) 
return arrayPageSize;
}

function showForm(formId){
 var pageInfo = getPageSize();
 document.getElementById('bLayer').style.top     = '0px';
 document.getElementById('bLayer').style.left    = '0px'; 
 document.getElementById('bLayer').style.width   = pageInfo[0]+'px';
 document.getElementById('bLayer').style.height  = pageInfo[1]+'px';  
 document.getElementById('bLayer').style.display = '';
 dispForm(pageInfo,formId);
}

function dispForm(pageInfo,formId){
   document.getElementById(formId).style.top     = pageInfo[1] / 3 + 'px';
   document.getElementById(formId).style.left    = (pageInfo[0] - parseInt(document.getElementById(formId).style.width)) / 2 + 'px';
   document.getElementById(formId).style.display = '';
}

function closeForm(formId){
  document.getElementById('bLayer').style.display = 'none';
  document.getElementById(formId).style.display = 'none';
}