function toggle(div_id)
{
    var el = document.getElementById(div_id);
    if ( el.style.display == 'none' ) {	el.style.display = 'block';}
    else { el.style.display = 'none';}
}

function blanket_size(popUpDivVar)
{
    if (typeof window.innerWidth != 'undefined')
    {
        viewportheight = window.innerHeight;
    }
    else
    {
        viewportheight = document.documentElement.clientHeight;
    }
    if ((viewportheight > document.body.parentNode.scrollHeight) && (viewportheight > document.body.parentNode.clientHeight))
    {
        blanket_height = viewportheight;
    }
    else
    {
        if (document.body.parentNode.clientHeight > document.body.parentNode.scrollHeight)
        {
            blanket_height = document.body.parentNode.clientHeight;
        }
        else
        {
            blanket_height = document.body.parentNode.scrollHeight;
        }
    }

    var blanket = document.getElementById('blanket');
    blanket.style.height = blanket_height + 'px';
    var popUpDiv = document.getElementById(popUpDivVar);
    popUpDiv_height=blanket_height/2-150;//150 is half popup's height
    popUpDiv.style.top = popUpDiv_height + 'px';
}

function window_pos(popUpDivVar)
{
    if (typeof window.innerWidth != 'undefined')
    {
        viewportwidth = window.innerHeight;
    }
    else
    {
        viewportwidth = document.documentElement.clientHeight;
    }
    
    if ((viewportwidth > document.body.parentNode.scrollWidth) && (viewportwidth > document.body.parentNode.clientWidth))
    {
        window_width = viewportwidth;
    }
    else
    {
        if (document.body.parentNode.clientWidth > document.body.parentNode.scrollWidth)
        {
            window_width = document.body.parentNode.clientWidth;
        }
        else
        {
            window_width = document.body.parentNode.scrollWidth;
        }
    }
    var popUpDiv = document.getElementById(popUpDivVar);
    window_width=window_width/2-150;//150 is half popup's width
    popUpDiv.style.left = window_width + 'px';
}

function popup(windowname)
{
    blanket_size(windowname);
    window_pos(windowname);
    toggle('blanket');
    toggle(windowname);		
}