Looks like we can't reproduce the issue or there's a problem in the test case provided.
CardLayout with a modal/centered item masks the parent itself
Please consider the following code:
The active item is Item 0, but still the parent panel is masked.
style: 'background-color: White; width: 400px; height: 500px',
I am not sure if that can be considered a bug, as it does not make sense to use a modal/centered window inside a card layout, but I hit it by chance and so reported it.
Thank you for the report.
Sencha - Sencha Touch Dev Team
This is correct behavior. Items can now be floatable/centered within other containers, not just the Viewport. This can be fairly handy on Tablet applications.
Does this mean that Touch team is considering the bug report as correct and the same has been fixed (so quickly)