Add an action and reducer for changing the thumbnail nav state

src/state/actions/action-types.js

@@ -12,6 +12,7 @@ const ActionTypes = {
   RECEIVE_MANIFEST: 'RECEIVE_MANIFEST',
   RECEIVE_MANIFEST_FAILURE: 'RECEIVE_MANIFEST_FAILURE',
   SET_CONFIG: 'SET_CONFIG',
+  SET_WINDOW_THUMBNAIL_POSITION: 'SET_WINDOW_THUMBNAIL_POSITION',
   TOGGLE_WINDOW_SIDE_BAR: 'TOGGLE_WINDOW_SIDE_BAR',
   UPDATE_CONFIG: 'UPDATE_CONFIG',
   REMOVE_MANIFEST: 'REMOVE_MANIFEST',

src/state/actions/window.js

@@ -50,3 +50,13 @@ export function removeWindow(windowId) {
 export function toggleWindowSideBar(windowId) {
   return { type: ActionTypes.TOGGLE_WINDOW_SIDE_BAR, windowId };
 }
+
+/**
+ * toggleWindowSideBar - action creator
+ *
+ * @param  {String} windowId
+ * @memberof ActionCreators
+ */
+export function setWindowThumbnailPosition(windowId, position) {
+  return { type: ActionTypes.SET_WINDOW_THUMBNAIL_POSITION, windowId, position };
+}

src/state/reducers/windows.js

@@ -22,6 +22,14 @@ const windowsReducer = (state = {}, action) => {
           sideBarOpen: !state[action.windowId].sideBarOpen,
         },
       };
+    case ActionTypes.SET_WINDOW_THUMBNAIL_POSITION:
+      return {
+        ...state,
+        [action.windowId]: {
+          ...state[action.windowId],
+          thumbnailNavigationPosition: action.position,
+        },
+      };
     case ActionTypes.NEXT_CANVAS:
       return setCanvasIndex(state, action.windowId, currentIndex => currentIndex + 1);
     case ActionTypes.PREVIOUS_CANVAS: