test cartlist lengths and document limitations and alternative method for scrollbar rendering

uxn-client/n/carts

@@ -34,3 +34,26 @@ and bizniss
 and buznets
 and whimsy
 and also combs
+noodle
+orca
+left
+ustrat
+katbug
+soul grind
+hyperkaos
+niju
+pokiminz
+yeet
+funk
+what
+is
+this
+bizzzz
+eele
+blunt
+junt
+hanf
+yank
+yunt
+yeet
+eee

uxn-client/xrxs.tal

@@ -548,6 +548,10 @@ RTN
 
 RTN
 
+( this scrollbar breaks down with about 2x as many cartridges as the scren
+  has room for. A better method would be keeping track of the height, step,
+  and position )
+
 @draw-scrollbar ( -> )
 
   .Screen/width DEI2 #0048 SUB2 .Screen/x DEO2
@@ -571,18 +575,17 @@ RTN
   &start-loop
   #0028 .Screen/y DEO2
   ( store the number of carts per tile of the scroll bar )
-  .ncarts LDZ .list-height LDZ SUB .list-height LDZ MOD INC
-  STH
+  .ncarts LDZ .list-height LDZ DIV STH
   
   .list-height LDZ #00
   &while EQUk ,&end JCN
     ( trough top ) 
-    DUP INC .list-top LDZ GTH ,&handle JCN
+    DUP INC STHrk MUL .list-top LDZ GTH ,&handle JCN
       INC
       INC-Y
       ,&while JMP
     &handle
-    DUP .list-top LDZ .list-height LDZ ADD STHrk SUB LTH #00 EQU ,&trough-bottom JCN
+    DUP INC INC STHrk .ncarts LDZ [ .list-top LDZ .list-height LDZ ADD ] SUB MUL ADD .list-height LDZ GTH ,&trough-bottom JCN
       ;scrollbar .Screen/addr DEO2
       #81 .Screen/sprite DEO
     &trough-bottom