/**
* Creates a popup window, centred in the middle of the screen and focused
*
* @param url - Url to launch in window
* @param hWnd - name of popup window (used to reference from callee window)
* @param w - width of window
* @param h - height of window
* @param params - parameters for the window, a string, i.e. "scrollbars=yes,toolbars=no" etc.
*/
function popUpWindow(url,hWnd, w, h,params)
{
	x = (screen.width - w) /2;
	y = (screen.height - h) /2;
	
	if (params != null) params = "," + params;
	popWin = window.open(url,hWnd,"top="+y+",left="+x+",width="+w+",height="+h+params);
	popWin.focus();
}
/* code library popup demos */
function showDemo(url)
{
	popUpWindow(url,'demo',600,400,'scrollbars=yes,resizable=no');
}