Some refactoring, more work on the custom theme generator

Logic/Web/LocalStorageSource.ts

@@ -0,0 +1,21 @@
+import {UIEventSource} from "../UIEventSource";
+
+export class LocalStorageSource {
+
+    static Get(key: string, defaultValue: string = undefined): UIEventSource<string> {
+
+        try {
+
+
+            const saved = localStorage.getItem(key);
+            const source = new UIEventSource<string>(saved ?? defaultValue);
+
+            source.addCallback((data) => {
+                localStorage.setItem(key, data);
+            });
+            return source;
+        } catch (e) {
+            return new UIEventSource<string>(defaultValue);
+        }
+    }
+}