function bg_getScrollWidth()
{
   var w = window.pageXOffset ||
           document.body.scrollLeft ||
           document.documentElement.scrollLeft;
           
   return w ? w : 0;
} 

function bg_getScrollHeight()
{
   var h = window.pageYOffset ||
           document.body.scrollTop ||
           document.documentElement.scrollTop;
           
   return h ? h : 0;
}

function bg_show_div(divid) {
document.getElementById(divid).style.display = 'block';
};

function bg_hide_div(divid) {
document.getElementById(divid).style.display = 'none';
};

function bg_showhide_div(divid) {
if (document.getElementById(divid).style.display == 'block')
{bg_hide_div(divid);} else {bg_show_div(divid);};



};




function bg_set_div_to_center(divid) {

Xwidth=document.getElementById(divid).offsetWidth;
Yheight=document.getElementById(divid).offsetHeight;

var scrolledX=bg_getScrollWidth();
var scrolledY=bg_getScrollHeight(); 


var centerX, centerY; 
if( self.innerHeight ) { 
centerX = self.innerWidth; 
centerY = self.innerHeight; 
} else if( document.documentElement && document.documentElement.clientHeight ) { 
centerX = document.documentElement.clientWidth; 
centerY = document.documentElement.clientHeight; 
} else if( document.body ) { 
centerX = document.body.clientWidth; 
centerY = document.body.clientHeight; 
} 

var leftoffset = scrolledX + (centerX - Xwidth) / 2; 
var topOffset = scrolledY + (centerY - Yheight) / 2; 


document.getElementById(divid).style.left=leftoffset; 
document.getElementById(divid).style.top=topOffset;


};