fixed crash in GUI when loading new file after stop
fixed crash in GUI when loading new file after stop

gpac/gpac,rbouqueau/gpac,gpac/gpac,gpac/gpac,rbouqueau/gpac,gpac/gpac,rbouqueau/gpac,gpac/gpac,RodolpheFouquet/gpac,RodolpheFouquet/gpac,gpac/gpac,rbouqueau/gpac,rbouqueau/gpac,rbouqueau/gpac,RodolpheFouquet/gpac,rbouqueau/gpac,RodolpheFouquet/gpac,gpac/gpac,rbouqueau/gpac,gpac/gpac,RodolpheFouquet/gpac,RodolpheFouquet/gpac