#include <u.h>#include <libc.h>#include <draw.h>#include <mouse.h>#include <cursor.h>#include <drawfcall.h> voidusage(void){	fprint(2, "usage: devdraw (don't run  directly)\n");	exits("usage");} voidmain(int argc, char **argv){	int n;	uchar buf[1024*1024];	Wsysmsg m;		ARGBEGIN{	case 'D':		break;	default:		usage();	}ARGEND		if(argc != 0)		usage(); 	while((n = readwsysmsg(0, buf, sizeof buf)) > 0){		convM2W(buf, n, &m);		m.type = Rerror;		m.error = "no window system present";		n = convW2M(&m, buf, sizeof buf);		write(1, buf, n);	}	exits(0);}