First sketch of layers

src/appbar.js

@@ -4,11 +4,24 @@ import AppBar from "material-ui/AppBar";
 import CircularProgress from "material-ui/CircularProgress";
 import MapIcon from "material-ui/svg-icons/maps/map";
 import PhonelinkOffIcon from "material-ui/svg-icons/hardware/phonelink-off";
+import LayersIcon from "material-ui/svg-icons/maps/layers";
 import IconMenu from "material-ui/IconMenu";
 import IconButton from "material-ui/IconButton";
 import MenuItem from "material-ui/MenuItem";
 import { orange400, grey50 } from "material-ui/styles/colors";
 
+const TopBarLayerSelector = (props: Object) => (
+  <IconMenu
+    iconButtonElement={
+      <IconButton style={{width: 48, height: 48, padding: 0}}
+          iconStyle={{width: 48, height: 48}}>
+        <LayersIcon color={grey50} />
+      </IconButton>}
+    style={{width:48, height:48}}>
+    <MenuItem primaryText="Layer1" />
+  </IconMenu>
+)
+
 const TopBarIndicatorMenu = (props: Object) => (
   <IconMenu
     iconButtonElement={
@@ -37,6 +50,7 @@ const TopBar = (props: Object) => (
   <AppBar title={props.title}
           style={{background:orange400}}
           iconElementLeft={<TopBarIndicator {...props} />}
+          iconElementRight={<TopBarLayerSelector {...props} />}
           className="nav"
   />);