Add color bounds

Can cycle with (1)

tisdraw.txt

@@ -1,11 +1,13 @@
 @0
-#ACC IS COLOR
-MOV 3 ACC
-SAV
+INIT:MOV 3 ACC
+SWP
 L:MOV ANY ACC
 JEZ SND
 SWP
 ADD RIGHT
+MOV 1 DOWN
+MOV ACC DOWN
+MOV DOWN ACC
 SAV
 JMP L
 SND:SWP
@@ -64,7 +66,19 @@ JMP B
 BIG:MOV 21 LAST
 
 @4
-MOV RIGHT UP
+B:MOV ANY ACC
+JEZ SND
+MOV UP ACC
+JLZ BAD
+SAV
+SUB 4
+JGZ BAD
+SWP
+MOV ACC UP
+JMP B
+BAD:MOV 4 UP
+JMP B
+SND:MOV ACC UP
 MOV UP RIGHT
 
 @5
@@ -92,7 +106,6 @@ SAV
 MOV RIGHT LEFT#Y
 
 @7
-#ACC IS Y
 B:MOV ANY ACC
 JEZ SND
 SWP