The below code loosely simulates how I implemented an overlay tutorial in my app using backgroundColor transparency, set via hex triplets. mainview and label represent app content. containerview is an overlay containing tutorial information, and masking view represents a view that 'darkens' the content until it needs to be highlighted. In the example below, it toggles the highlighting by setting the maskingview backgroundColor alpha to either 0 or 90% when you click the view.
Expected result is the alpha of the maskingview backgroundColor changes and the mainview content is visible or masked. Works on both Android and iOS using SDK 5.4.0.GA. Works on iOS using SDK 6.1.0.GA, but not Android. Commenting out setting borderRadius on the maskingview (issue is both at create or runtime) solves the problem on Android.
Steps to reproduce: uncomment the borderRadius setter below, build with 5.4.0.GA on Android. Expected result: clicking on view fades or shows the underlying "Hello". Rebuild with 6.1.0.GA on Android, clicking on view complete hides the underlying view. Comment out borderRadius setter under 6.1.0.GA, works as expected again.