var win_popup = null; // window handle
var win_popup_open = false; // open flag

// opens a popup windows displaying [pageURL] of width [winWidth] and height [winHeight]
function wg_popwindow(pageURL, winWidth, winHeight)
{    
    // if popup already open, close it to ensure it pops to the front
    if (win_popup_open) 
    {
        win_popup_open = false;
        win_popup.close();
    }
    win_popup = window.open(pageURL,"popwin","width="+winWidth+",height="+winHeight+",menubar=no,resizable=no,scrollbars=no,status=no,toolbar=no,titlebar=no");
    win_popup_open = true;
}

// callback function for when window is opened
function wg_opened()
{
}

// callback function for when window is closed
function wg_closed()
{
    win_popup_open = false; // set flag
    win_popup = null; // destroy handle
}