extern fg_time_t fgPlatformSystemTime ( void );
extern void fgPlatformSleepForEvents( fg_time_t msec );
extern void fgPlatformProcessSingleEvent ( void );
extern fg_time_t fgPlatformSystemTime ( void );
extern void fgPlatformSleepForEvents( fg_time_t msec );
extern void fgPlatformProcessSingleEvent ( void );