diff --git a/dot-to-dot b/dot-to-dot
index 1cec769..84ecf9d 100755
Binary files a/dot-to-dot and b/dot-to-dot differ
diff --git a/dot-to-dot.mlb b/dot-to-dot.mlb
index 8b2a57d..f91b646 100644
--- a/dot-to-dot.mlb
+++ b/dot-to-dot.mlb
@@ -27,9 +27,5 @@ in
 end
 
 imperative-shell/input-callbacks.sml
-
-ann
-  "allowVectorExps true"
-in
-  imperative-shell/shell.sml
-end
+imperative-shell/event-loop.sml
+imperative-shell/shell.sml
diff --git a/imperative-shell/app-draw.sml b/imperative-shell/app-draw.sml
index 466a556..c6c07b7 100644
--- a/imperative-shell/app-draw.sml
+++ b/imperative-shell/app-draw.sml
@@ -93,7 +93,7 @@ struct
       ()
     end
 
-  fun drawButton (buttonDrawObject: draw_object, vec) =
+  fun drawButton (buttonDrawObject: draw_object, buttonDrawLength) =
     let
       val {vertexBuffer, program, ...} = buttonDrawObject
       val _ = Gles3.bindBuffer vertexBuffer
@@ -102,7 +102,7 @@ struct
       val _ = Gles3.vertexAttribPointer (1, 3, 5, 8)
       val _ = Gles3.enableVertexAttribArray 1
       val _ = Gles3.useProgram program
-      val _ = Gles3.drawArrays (Gles3.TRIANGLES (), 0, Vector.length vec div 5)
+      val _ = Gles3.drawArrays (Gles3.TRIANGLES (), 0, buttonDrawLength)
     in
       ()
     end
diff --git a/imperative-shell/event-loop.sml b/imperative-shell/event-loop.sml
new file mode 100644
index 0000000..81d0257
--- /dev/null
+++ b/imperative-shell/event-loop.sml
@@ -0,0 +1,35 @@
+structure EventLoop =
+struct
+  open CML
+  open InputMessage
+
+  fun update inputMailbox =
+    let
+      val _ =
+        case Mailbox.recv inputMailbox of
+          MOUSE_MOVE {x, y} =>
+            print (String.concat
+              ["x pos: ", Int.toString x, ", y pos: ", Int.toString y, "\n"])
+        | MOUSE_LEFT_CLICK => print "clicked mouse\n"
+        | MOUSE_LEFT_RELEASE => print "released mouse\n"
+    in
+      update inputMailbox
+    end
+
+  fun draw (window, graphDrawObject, buttonDrawObject, buttonDrawLength) =
+    if not (Glfw.windowShouldClose window) then
+      let
+        val _ = Gles3.clearColor (1.0, 1.0, 1.0, 1.0)
+        val _ = Gles3.clear ()
+
+        val _ = AppDraw.drawGraphLines graphDrawObject
+        val _ = AppDraw.drawButton (buttonDrawObject, buttonDrawLength)
+
+        val _ = Glfw.pollEvents ()
+        val _ = Glfw.swapBuffers window
+      in
+        draw (window, graphDrawObject, buttonDrawObject, buttonDrawLength)
+      end
+    else
+      Glfw.terminate ()
+end
diff --git a/imperative-shell/shell.sml b/imperative-shell/shell.sml
index 0077ece..9cda3f9 100644
--- a/imperative-shell/shell.sml
+++ b/imperative-shell/shell.sml
@@ -2,37 +2,6 @@ structure Shell =
 struct
   open CML
 
-  fun callbackListener mailbox =
-    let
-      open InputMessage
-      val _ =
-        case Mailbox.recv mailbox of
-          MOUSE_MOVE {x, y} =>
-            print (String.concat
-              ["x pos: ", Int.toString x, ", y pos: ", Int.toString y, "\n"])
-        | MOUSE_LEFT_CLICK => print "clicked mouse\n"
-        | MOUSE_LEFT_RELEASE => print "released mouse\n"
-    in
-      callbackListener mailbox
-    end
-
-  fun loop (window, graphDrawObject, buttonDrawObject) =
-    if not (Glfw.windowShouldClose window) then
-      let
-        val _ = Gles3.clearColor (1.0, 1.0, 1.0, 1.0)
-        val _ = Gles3.clear ()
-
-        val _ = AppDraw.drawGraphLines graphDrawObject
-        val _ = AppDraw.drawButton (buttonDrawObject, #[])
-
-        val _ = Glfw.pollEvents ()
-        val _ = Glfw.swapBuffers window
-      in
-        loop (window, graphDrawObject, buttonDrawObject)
-      end
-    else
-      Glfw.terminate ()
-
   fun main () =
     let
       (* Set up GLFW. *)
@@ -63,9 +32,9 @@ struct
           ()
         end)
       (* Set callback listener *)
-      val _ = CML.spawn (fn () => callbackListener inputMailbox)
+      val _ = CML.spawn (fn () => EventLoop.update inputMailbox)
     in
-      loop (window, graphDrawObject, buttonDrawObject)
+      EventLoop.draw (window, graphDrawObject, buttonDrawObject, 0)
     end
 end