render start/end marks on time axis

they don't do anything yet

frontend/src/Main.elm

@@ -191,7 +191,7 @@ type Msg
   | Loaded (Result Http.Error (List Point))
   | NewUrlRequest
   | UrlChanged
-
+  | Dribble String
 
 update : Msg -> Model -> (Model, Cmd Msg)
 
@@ -247,6 +247,9 @@ updateModel msg model =
                 Err e -> { model | track = Debug.log "unknown error" (Failure "e") }
         NewUrlRequest -> model
         UrlChanged ->  model
+        Dribble message ->
+            let _ = Debug.log "dribble" message
+            in model
 
 
 -- VIEW
@@ -400,6 +403,9 @@ measureView title colour fn allPoints =
         , xtick 5
         ]
 
+timeClickDecoder  =
+    D.map Dribble  (D.at ["target", "id"] D.string)
+
 timeAxis allPoints =
     let filteredPoints = Point.downsample 300 allPoints
         graphHeight = 30
@@ -439,13 +445,35 @@ timeAxis allPoints =
              , fill "#eef"
              , stroke "none"
              ] []
+        markStart x =
+            let x1 = String.fromInt x
+            in Svg.path
+                [ S.d ("M " ++ x1 ++ " 40 " ++
+                         "v -50 h 10 v 10 h -10 v -10")
+                , fill "#7c7"
+                , stroke "#4e4"
+                , H.id "left-marker"
+                , strokeWidth "3"
+                ] []
+        markEnd x =
+            let x1 = String.fromInt x
+            in Svg.path
+                [ S.d ("M " ++ x1 ++ " 40 " ++
+                         "v -50 h -10 v 10 h 10 v -10")
+                , fill "#c77"
+                , stroke "#e44"
+                , H.id "right-marker"
+                , strokeWidth "3"
+                ] []
     in
         svg
         [ width portalWidth
-        , height graphHeight
-        , preserveAspectRatio "none"
+        , height (graphHeight + 20)
+        , on "pointerdown" timeClickDecoder
+        , viewBox ("0 -10 " ++ (String.fromInt portalWidth) ++
+                       "  " ++ (String.fromInt (graphHeight + 10)))
         ]
-        (bg::xticks)
+        (bg::(markStart 22)::(markEnd 422)::xticks)
 
 
 cadenceView : List Point -> Svg Msg