moved GUI project to a subdirectory.

GUI/EnterMaskDialog.xaml.cs

@@ -0,0 +1,33 @@
+using System.Collections.Generic;
+using System.Windows;
+using System.Windows.Controls;
+using System.Windows.Input;
+
+namespace GARbro.GUI
+{
+    /// <summary>
+    /// Interaction logic for EnterMaskDialog.xaml
+    /// </summary>
+    public partial class EnterMaskDialog : Window
+    {
+        public EnterMaskDialog (IEnumerable<string> mask_list)
+        {
+            InitializeComponent ();
+            Mask.ItemsSource = mask_list;
+            Mask.Text = "*.*";
+        }
+
+        private void Button_Click (object sender, RoutedEventArgs e)
+        {
+            this.DialogResult = true;
+        }
+        
+        private void Mask_Loaded (object sender, RoutedEventArgs e)
+        {
+            var text_box = (TextBox)Mask.Template.FindName ("PART_EditableTextBox", Mask);
+            FocusManager.SetFocusedElement (this, text_box);
+            text_box.SelectionStart = 2;
+            text_box.SelectionLength = 1;
+        }
+    }
+}