Ways to reproduce:
1. Launch the app.
2. The Popup manager add a popup with custom busy indicator with this line of code PopUpManager.addPopUp(progress, this, true);
3. Tap touch the screen in your device or click the emulator on your PC while the busy indicator is still running.
3. Uncatch error occurs and the app crashes.
Note: This error does not occur when I set the modal=false. E.g. PopUpManager.addPopUp(progress, this, false);