Give contextual feedback for manual update check instead of banner

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

src/hooks/useDispatcher.ts

@@ -0,0 +1,40 @@
+/*
+Copyright 2020 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import {useEffect, useRef} from "react";
+
+import {ActionPayload} from "../dispatcher/payloads";
+import {Dispatcher} from "flux";
+
+// Hook to simplify listening to flux dispatches
+export const useDispatcher = (dispatcher: Dispatcher<ActionPayload>, handler: (payload: ActionPayload) => void) => {
+    // Create a ref that stores handler
+    const savedHandler = useRef((payload: ActionPayload) => {});
+
+    // Update ref.current value if handler changes.
+    useEffect(() => {
+        savedHandler.current = handler;
+    }, [handler]);
+
+    useEffect(() => {
+        // Create event listener that calls handler function stored in ref
+        const ref = dispatcher.register((payload) => savedHandler.current(payload));
+        // Remove event listener on cleanup
+        return () => {
+            dispatcher.unregister(ref);
+        };
+    }, [dispatcher]);
+};