set showing as dialog with search

lib/selectionDialog.dart

@@ -0,0 +1,51 @@
+import 'package:flutter/material.dart';
+import 'package:country_code_picker/celement.dart';
+
+class SelectionDialog extends StatefulWidget {
+  final List<CElement> elements;
+
+  SelectionDialog(this.elements);
+
+  @override
+  State<StatefulWidget> createState() => new _SelectionDialogState();
+}
+
+class _SelectionDialogState extends State<SelectionDialog> {
+  List<CElement> showedElements = [];
+
+  @override
+  Widget build(BuildContext context) => new SimpleDialog(
+      title: new TextField(
+        decoration: new InputDecoration(prefixIcon: new Icon(Icons.search)),
+        onChanged: _filterElements,
+      ),
+      children: showedElements
+          .map((e) => new SimpleDialogOption(
+              child: new Text(e.toLongString()),
+              onPressed: () {
+                _selectItem(e);
+              }))
+          .toList());
+
+  @override
+  void initState() {
+    showedElements = widget.elements;
+    super.initState();
+  }
+
+  void _filterElements(String s) {
+    s = s.toUpperCase();
+    setState(() {
+      showedElements = widget.elements
+          .where((e) =>
+              e.code.contains(s) ||
+              e.dial_code.contains(s) ||
+              e.name.toUpperCase().contains(s))
+          .toList();
+    });
+  }
+
+  void _selectItem(CElement e) {
+    Navigator.pop(context, e);
+  }
+}