"in progress" indication when closing the app

[jeromeip]

Hi,

As the closing of Songkong app may take a significant time, I would add some indicator aknowleging the closing request, so that we are not surprised that the window is not closing immediately.

Regards,

[paultaylor]

Okay, logged as https://jthink.atlassian.net/browse/SONGKONG-2055