Fix back button; add title

Logic/Actors/HistoryHandling.ts

@@ -0,0 +1,19 @@
+import {UIEventSource} from "../UIEventSource";
+import {UIElement} from "../../UI/UIElement";
+
+export default class HistoryHandling {
+
+    constructor(hash: UIEventSource<string>, fullscreenMessage: UIEventSource<{ content: UIElement, hashText: string }>) {
+        hash.addCallback(h => {
+            if (h === undefined || h === "") {
+                fullscreenMessage.setData(undefined);
+            }
+        })
+        
+        fullscreenMessage.addCallback(fs => {
+            hash.setData(fs?.hashText);
+        })
+        
+    }
+
+}