void AddGrowableCol( size_t idx, int proportion = 0 );
void RemoveGrowableCol( size_t idx );
void AddGrowableCol( size_t idx, int proportion = 0 );
void RemoveGrowableCol( size_t idx );
// the sizer cells may grow in both directions, not grow at all or only
// grow in one direction but not the other
// the sizer cells may grow in both directions, not grow at all or only
// grow in one direction but not the other