diff --git a/visualisers/gmvis/public/css/main.css b/visualisers/gmvis/public/css/main.css
index 5cfc8c7..134a342 100644
--- a/visualisers/gmvis/public/css/main.css
+++ b/visualisers/gmvis/public/css/main.css
@@ -25,35 +25,49 @@ body
 { margin: 0
 ; padding: 0
 ; overflow: scroll
+; display: flex
+; flex-direction: column
 }
 
 .pane-content
 { margin: 0.5em
 }
 
-.pane-content h5
+.view-header
 { margin: 0
-}
-
-.split-pane:has(> .stack-view)
-{ display: flex
-; flex-direction: column-reverse
+; flex-shrink: 0
 }
 
 .stack-view
 { display: flex
+; flex-direction: column
+; justify-content: space-between
+
+/* to fill the container */
+; flex-grow: 1
+}
+
+.stack-entry-container
+{ display: flex
 ; flex-direction: column-reverse
 ; align-content: flex-end
 }
 
-.stack-view > .stack-entry:nth-of-type(odd)
+.stack-entry-container.even > .stack-entry:nth-of-type(even)
 { background: #0000007f
+; color: white
+}
+
+.stack-entry-container.odd > .stack-entry:nth-of-type(odd)
+{ background: #0000007f
+; color: white
 }
 
 .stack-entry
 { display: flex
 ; flex-direction: row
 ; justify-content: space-between
+; font-family: monospace;
 }
 
 .stack-entry-addr
@@ -67,14 +81,46 @@ body
 .heap-view
 {}
 
+/* .split-pane:has(> .code-view) */
+/* { overflow: hidden */
+/* } */
+
 .code-view
+{ display: flex
+; flex-direction: column
+; align-items: stretch
+; align-content: stretch
+; justify-content: flex-start
+; flex-grow: 1
+}
+
+.code-view .code-instr-container
 { display: grid
+; overflow: scroll
+; flex-shrink: 4
+; min-height: 0
 }
 
-.code-view.instr
-{}
+.code-view .instr
+{ font-family: monospace;
+}
 
-.code-view > .instr:nth-of-type(odd)
+.code-instr-container.even > .instr:nth-of-type(even)
 { background: #0000007f
+; color: white
+}
+
+.code-instr-container.odd > .instr:nth-of-type(odd)
+{ background: #0000007f
+; color: white
+}
+
+.code-view .code-button-container
+{ display: flex
+; flex-direction: row
+/* ; align-self: flex-end */
+; justify-content: space-between
+; margin-top: auto
+; flex-shrink: 0
 }
 
diff --git a/visualisers/gmvis/src/ui.cljs b/visualisers/gmvis/src/ui.cljs
index 19d040c..2d77719 100644
--- a/visualisers/gmvis/src/ui.cljs
+++ b/visualisers/gmvis/src/ui.cljs
@@ -15,7 +15,8 @@
 ;------------------------------------------------------------------------------;
 
 (def current-evaluation (r/atom []))
-(def current-index (r/atom 5))
+; (def current-index (r/atom 5))
+(defonce current-index (r/atom 0))
 
 (def +split-width+ "4px")
 
@@ -33,47 +34,87 @@
   [:> Resplit.Splitter (assoc props :class "split-splitter")
    [:<> children]])
 
+(defn Header [text]
+  [:h5 {:class "view-header"}
+   text])
+
 ;------------------------------------------------------------------------------;
 
 (defn Dump []
   [:div {:class "pane-content dump-view"}
-   [:h1 "Dump"]])
+   [Header "Dump"]])
 
 (defn Heap []
   [:div {:class "pane-content heap-view"}
-   [:h1 "Heap"]])
+   [Header "Heap"]])
+
+(defn gen-key []
+  (js/self.crypto.randomUUID))
+
+(defn add-key [e]
+  (let [uuid (js/self.crypto.randomUUID)]
+    (match e
+      [tag props & children] (concat [tag (assoc props :key uuid)] children))))
 
 ;------------------------------------------------------------------------------;
 
 (defn deref-addr [heap addr]
   (get heap
        (keyword (str addr))
-       (str "<broken pointer: &" addr ">")))
+       nil))
 
 (defn words [& ws]
   (->> ws
        (map str)
        (str/join \space)))
 
-(defn ppr-node [heap n]
-  (match n
+(defn maybe-parens [c s]
+  (if c
+      (str "(" s ")")
+      s))
+
+(def app-prec 10)
+(def app-prec+1 11)
+(def app-prec-1 9)
+
+(defn ppr-node* [p heap addr]
+  (match (deref-addr heap addr)
     {:tag "NGlobal" :contents [arity code]}
-    (words "Global" arity "<code>")
+    (maybe-parens (> p 0)
+                  (words "Global" arity "<code>"))
 
     {:tag "NNum" :contents k}
-    (words "Num" k)
+    (maybe-parens (> p 0)
+                  (words "Num" k))
+
+    {:tag "NAp" :contents [f x]}
+    (maybe-parens (> p app-prec)
+                  (words "App"
+                         (ppr-node* app-prec heap f)
+                         (ppr-node* app-prec+1 heap x)))
+
+    nil (str "<broken pointer: &" addr ">")
+
     a (str "other" a)))
 
+(defn ppr-node [heap addr]
+  (ppr-node* 0 heap addr))
+
 (defn StackEntry [heap addr]
-  (let [node (deref-addr heap addr)]
-    [:div {:class "stack-entry"}
-     (ppr-node heap node)
-     [:div {:class "stack-entry-addr"}
-      (str "&" addr)]]))
+  [:div {:class "stack-entry"
+         :key (gen-key)}
+   (ppr-node heap addr)
+   [:div {:class "stack-entry-addr"}
+    (str "&" addr)]])
+
+(defn StackEntryContainer [children]
+  [:div {:class "stack-entry-container even"}
+   [:<> children]])
 
 (defn Stack [heap s]
   [:div {:class "pane-content stack-view"}
-   [:<> (map (partial StackEntry heap) s)]])
+   [Header "Stack"]
+   [StackEntryContainer (map (partial StackEntry heap) (reverse s))]])
 
 #_ (swap! current-index #(+ % 1))
 #_ (swap! current-index #(- % 1))
@@ -81,16 +122,34 @@
 ;------------------------------------------------------------------------------;
 
 (defn ppr-instr [{op :tag c :contents}]
-  (str op " " c))
+  (match op
+    "CaseJump" (words op "<cases>")
+    _ (words op c)))
 
 (defn Instr [instr]
-  [:code {:class "instr"}
+  [:code {:class "instr"
+          :key (gen-key)}
    (ppr-instr instr)])
 
+(defn CodeButtons []
+  [:div {:class "code-button-container"}
+   [:button {:onClick #(swap! current-index dec)}
+    "<"]
+   [:code @current-index]
+   [:button {:onClick #(swap! current-index inc)}
+    ">"]])
+
+(defn CodeInstrContainer [children]
+  [:div {:class (if (even? (count children))
+                    "code-instr-container even"
+                    "code-instr-container odd")}
+   [:<> children]])
+
 (defn Code [code]
   [:div {:class "pane-content code-view"}
-   [:h5 "Next instructions"]
-   [:<> (map Instr code)]])
+   [Header "Next instructions"]
+   [CodeInstrContainer (map Instr code)]
+   [CodeButtons]])
 
 ;------------------------------------------------------------------------------;