call mounted recursively on all children

src/core/widget.ts

@@ -59,7 +59,7 @@ export default class Widget {
     if (target) {
       target.appendChild(this.el!);
       if (document.body.contains(target)) {
-        this.mounted();
+        this.visitSubTree(w => w.mounted())
       }
     }
     return vnode;
@@ -102,4 +102,11 @@ export default class Widget {
     this.vnode = vnode;
     return vnode;
   }
+
+  private visitSubTree(callback: (w: Widget) => void) {
+    callback(this);
+    for (let child of this.children) {
+      child.visitSubTree(callback);
+    }
+  }
 }