//------------------------------------------------------------------------------
var newwindow = '';

function popup(url,width,height,window_name,win_settings){
	if(!width) width = 600;
  if(!height) height = 400;
  if(!window_name) window_name = 'newwindow';
  if(!win_settings) win_settings = ',resizable=1,scrollbars=1';
	var left   = (screen.width  - width)/2;
	var top    = (screen.height - height)/2;
	newwindow = window.open(url,window_name,'width='+width+',height='+height+', top='+top+', left='+left+win_settings);
	newwindow.focus();
}