GB_myShow = function(caption, url, /* optional */ height, width, callback_fn) 
 { 
	 //alert(url);
 var options = {        
 caption: caption,
 center_win:true,        
 height: height || 420,        
 width: width || 510,        
 fullscreen: false,
 show_loading: true,        
 callback_fn: callback_fn    
 }    
 var win = new GB_Window(options);
 return win.show(url);}