void endX(){end = true;	Sleep(2000);}	

GUI_APP_MAIN{
	GPSx2().Run();
	...
	...
	endX();

// and then in each thread
	    Sleep(1000);	
		while (CommPort.ReadDataWaiting() ) {
			if(end) break;
		  try{
// with global
void endX();
bool end;