[AC-729] Window Focus event Fire some times fire and some times it doesn't. Even app get hangs up and next window is not opening.

My application was running good with titanium sdk 3.4.0, but after updating the titanium SDK 3.5.1 and Titanium SDK 4.0 Beta, both version I am facing the same problem. Focus event some time fire for the window and some time it doesn't, I has created the application with JS pattern using Ti.UI.current window object and that application is created 1.5 years before, I always make the app compatible to the newer sdk which gets launch up. But with current sdk app is completely get disturbed and has lots of bugs, only because of the problem that window Focus event doesn't fire properly, due to this window get hangs up. I have created the sample application which can exactly reproduce this issue. Request for the appcelerator team to take this issue very seriously. Step To reproduce the issue: Run the application on iOS 1. Click on Open Blue Window. 2.Alert dialog will appear, click on Confirm. 3. Second window In blue color will get open. 4. On second window on top right navigation bar click on "Open third window" 5. On 3 window with pink color will get open, click on "Close pink window" Now when you go back to second window, second window focus will not fire, and then you navigate to first window, first window focus will not fire. Even the application will get hang, all the buttons will stop working and even next window doesn't get opens up on click of "open click window.