titanium mobile navgroup.open transition before new window fully rendered
===

I'm currently working on an iPad App and ran into the following Issue.

When I'm trying to open a new window which contains a set of buttons, which are created in a loop, during the transition only the first button is visible, the rest will be rendered after the new window is visible. Looks awful, and I can't figure out a way to "wait" with sliding until everything is in place (kinda like jquery's ready, or a callback when DOM-Elements are loaded).

Here's what I'm doing:

    clicker.addEventListener('click', function(e){    
      var overview = Ti.UI.createWindow( {
        title : "Overview",
        barColor: '#000',
        layout : 'vertical',
        url: '/views/overview.js',
        _parent: Titanium.UI.currentWindow,
        navGroup : navGroup,
        rootWindow : win1
      });
    
      navGroup.open(overview, {animated:true});
    });

and in overview.js I do the following:

    var overviewdata = [/*some data*/];
    for(var i = 0;i < overviewdata.length;i++){
	//calculations for proper positioning
	if(i == 0 || i%4 == 0){
		toppx = 30;
		leftpx = 40;
	}
	else
	{
		leftpx += 245;
		toppx = -200;
	}
	
	overviewbttns[i] = Ti.UI.createButton({ 
		title: overviewdata[i].title,
		backgroundImage:"/images/views/button.png",
		width: 200,
		height: 200,
		left: leftpx,
		top: toppx,
		id: i
	});
	
	//add to window
	win.add(overviewbttns[i]);
	
	//attach event handler
	overviewbttns[i].addEventListener('click',function(e){
		
	    var w = Ti.UI.createWindow( {
	        title : overviewdata[e.source.id].title,
	        barColor: '#000',
	        layout : 'vertical',
	        url: "/views/"+overviewdata[e.source.id].jsfile,
	        _parent: Titanium.UI.currentWindow,
	        navGroup : win.navGroup,
	        rootWindow : win.rootWindow        
	    });
	    
	    win.navGroup.open(w);
	});
	
    }

So, is there a way to get a callback/event when the overview window is fully rendered?

Any hints are appreciated, I'm really stuck here.

Thanks in advance!