C=1
MOUSE 0 : MOUSE 1,10,10,1
MOUSE 4,0,0,639,399
   LINE (0,0)-(639,399),PSET,6,B
*B
IF MOUSE(2,0)=-1 THEN IX1=MOUSE(0):IY1=MOUSE(1):GOTO *A
GOTO *B
*A
 IX2=MOUSE(0):IY2=MOUSE(1)
'if mouse(2,0)=-1 then line(IX1,IY1)-(IX2,IY2),pset,C
 B=IX2-IX1
 IF B<3  THEN B=3
 IF MOUSE(2,0)=-1 THEN CIRCLE@(IX1,IY1),B,C,,,,F
 IF MOUSE(2,1)=-1 THEN GOTO 20
 C=C+1
 IF C>7 THEN C=1
 GOTO *A