[Bug-gnubg] Crash after doubling cube for first time

[Camacnee]

I expect that this has been reported many times: On some occasions a crash results if I click on the doubling cube when the program has not already doubled. Under other circumstances (I can't tell what they are, but possibly that in a previous game in the session the program has doubled first) it does not happen. It has never happened when the program has already doubled in the current game.

Kind regards

Colin Macnee