optimize<FoldDialog, NewPage>: 修改欢迎页的打开本地仓库的弹出窗口为模态窗口

src/UI/FolderDailog.xaml.cs

@@ -121,8 +121,29 @@ namespace SourceGit.UI {
         /// <param name="onOK"></param>
         public static void Open(string title, Action<string> onOK) {
             new FolderDailog(title, onOK).Show();
+        }
+
+        /// <summary>
+        ///     modeless.
+        /// </summary>
+        /// <param name="title"></param>
+        /// <param name="onOK"></param>
+        public static void Show(string title, Action<string> onOK)
+        {
+            new FolderDailog(title, onOK).Show();
         }
 
+        /// <summary>
+        ///     modal.
+        /// </summary>
+        /// <param name="title"></param>
+        /// <param name="onOK"></param>
+        public static void ShowDialog(string title, Action<string> onOK)
+        {
+            new FolderDailog(title, onOK).ShowDialog();
+        }
+
+
         #region EVENTS
         private void OnSure(object sender, RoutedEventArgs e) {
             if (selected != null) cb?.Invoke(selected.Path);

src/UI/NewPage.xaml.cs

@@ -42,7 +42,7 @@ namespace SourceGit.UI {
         /// <param name="sender"></param>
         /// <param name="e"></param>
         private void OpenOrAddRepo(object sender, RoutedEventArgs e) {
-            FolderDailog.Open(App.Text("NewPage.OpenOrInitDialog"), path => {
+            FolderDailog.ShowDialog(App.Text("NewPage.OpenOrInitDialog"), path => {
                 CheckAndOpenRepo(path);
             });
         }