OS X 10.9.4: Sometimes UI is not responding (Qt 5.2.0)

1)Build attached "Sample_App.zip" with Qt 5.2.0
2)You need to copy the html folder into Test.App/Contents/MacOS/. This html will be present in the attached "Sample_App.zip"
3)Bundle all the Qt libraries into Test.App
4)Now copy the Test.app into /Application folder
5)Now start running the Test.app with two different users on Mac
6)Soon after launching the application you will see the items 1)MusicLibrary 2)TESTP 3)TESTP and 4)TESTP
7)You click on Music Library, it will display many items - playlists,artists,albums,songs,genre,compilations,composers.
Here you select on any items now spinner keeps on rotating.

With two users start using the application according the steps above.
Stay logged in with one user for 30 seconds and then switch to second user
->UI won't respond, for example the back button on the spinner screen will not respond.
If window minimize, maximize or resize button is clicked the UI will start responding again.

Note: The issue can be reproduced only sometimes and reproduces only with Qt 5.2.0 on OS X 10.9.4. Personally I wasn't able to reproduce this issue.