BadTokenException in BillingReceiver

[nickkadrov]

Hi,

First of all thak you for you nice library. It's really help me.

From time to time I've get this exeption from my users:
java.lang.RuntimeException: Unable to start receiver net.robotmedia.billing.BillingReceiver: android.view.WindowManager$BadTokenException: Unable to add window -- token android.os.BinderProxy@41e718e8 is not valid; is your activity running?

I'm using AbstractBillingObserver for handling purchase process (not the activity version). As I understand sometimes for some reason Activity that I had put to Observer allready dead at the end of purchase.
What is the proper way to handel this situation?