[TIMOB-5970] iPad: Once Titanium.Media.openPhotoGallery is called, it can not be cancelled.

Once "Titanium.Media.openPhotoGallery" is called, you can not cancel it. There is no such "cancel" button as shown on iPhone. If you click twice outside the photo gallery, an error will be generated.

Repro Steps

Step 1: create a project to run the example code below. Step 2: click on the space outside the photo gallery. Step 3: click again on the space outside the photo gallery, the "error" alert will be popped up.

var win = Ti.UI.createWindow({ backgroundColor: '#000' });

win.addEventListener('click', function(){
   Titanium.Media.openPhotoGallery({

       success:function(event)
       {
           alert('success');
       },
       cancel:function(cancel)
       {
           alert('cancel');
       },
       error:function(error)
       {
           alert('error');
       }
   });
})

win.open();