feature<Checkout>: add a status panel for checkout progress

src/Views/Popups/Checkout.xaml.cs

@@ -0,0 +1,34 @@
+using System.Threading.Tasks;
+
+namespace SourceGit.Views.Popups {
+
+    /// <summary>
+    ///     切换分支
+    /// </summary>
+    public partial class Checkout : Controls.PopupWidget {
+        private string repo;
+        private string branch;
+
+        public Checkout(string repo, string branch) {
+            this.repo = repo;
+            this.branch = branch;
+
+            InitializeComponent();
+        }
+
+        public override string GetTitle() {
+            return App.Text("BranchCM.Checkout", branch);
+        }
+
+        public override Task<bool> Start() {
+            UpdateProgress(GetTitle());
+
+            return Task.Run(() => {
+                Models.Watcher.SetEnabled(repo, false);
+                new Commands.Checkout(repo).Branch(branch, UpdateProgress);
+                Models.Watcher.SetEnabled(repo, true);
+                return true;
+            });
+        }
+    }
+}