feature<Dashboard>: add context menu "Tracking" to change upstream of selected local branch

src/Git/Branch.cs

@@ -153,6 +153,19 @@ namespace SourceGit.Git {
             if (errs != null) App.RaiseError(errs);
         }
 
+        /// <summary>
+        ///     Change upstream
+        /// </summary>
+        /// <param name="repo"></param>
+        /// <param name="upstream"></param>
+        public void SetUpstream(Repository repo, string upstream) {
+            var errs = repo.RunCommand($"branch {Name} -u {upstream}", null);
+            if (errs != null) App.RaiseError(errs);
+
+            repo.Branches(true);
+            repo.OnBranchChanged?.Invoke();
+        }
+
         /// <summary>
         ///     Delete branch.
         /// </summary>

src/Git/Repository.cs

@@ -835,6 +835,18 @@ namespace SourceGit.Git {
             return cachedBranches;
         }
 
+        /// <summary>
+        ///     Get all remote branches
+        /// </summary>
+        /// <returns>All remote branches</returns>
+        public List<Branch> RemoteBranches() {
+            var ret = new List<Branch>();
+            foreach (var b in cachedBranches) {
+                if (!b.IsLocal) ret.Add(b);
+            }
+            return ret;
+        }
+
         /// <summary>
         ///     Get current branch
         /// </summary>

src/Resources/Styles/ContextMenu.xaml

@@ -61,7 +61,9 @@
                 <Path Grid.Column="2" Width="8" Height="8" Style="{DynamicResource Style.Icon}" Data="M 0 0 L 0 7 L 4 3.5 Z"/>
                 <Popup Name="Popup" Placement="Right" HorizontalOffset="-2" IsOpen="{TemplateBinding IsSubmenuOpen}" AllowsTransparency="True" Focusable="False" PopupAnimation="Fade">
                     <Border Name="SubmenuBorder" SnapsToDevicePixels="True" Background="{DynamicResource Brush.BG1}" BorderBrush="{DynamicResource Brush.Border1}" BorderThickness="1">
-                        <StackPanel IsItemsHost="True" KeyboardNavigation.DirectionalNavigation="Cycle"/>
+                        <ScrollViewer HorizontalScrollBarVisibility="Disabled" VerticalScrollBarVisibility="Auto" CanContentScroll="True">
+                            <StackPanel IsItemsHost="True" KeyboardNavigation.DirectionalNavigation="Cycle"/>
+                        </ScrollViewer>
                     </Border>
                 </Popup>
             </Grid>

src/UI/Dashboard.xaml.cs

@@ -641,14 +641,14 @@ namespace SourceGit.UI {
             if (branch.Kind != Git.Branch.Type.Normal) {
                 menu.Items.Add(new Separator());
 
-                var icon = new System.Windows.Shapes.Path();
+                var flowIcon = new System.Windows.Shapes.Path();
-                icon.Style = FindResource("Style.Icon") as Style;
+                flowIcon.Style = FindResource("Style.Icon") as Style;
-                icon.Data = FindResource("Icon.Flow") as Geometry;
+                flowIcon.Data = FindResource("Icon.Flow") as Geometry;
-                icon.Width = 10;
+                flowIcon.Width = 10;
 
                 var finish = new MenuItem();
                 finish.Header = $"Git Flow - Finish '{branch.Name}'";
-                finish.Icon = icon;
+                finish.Icon = flowIcon;
                 finish.Click += (o, e) => {
                     GitFlowFinishBranch.Show(repo, branch);
                     e.Handled = true;
@@ -693,6 +693,39 @@ namespace SourceGit.UI {
             menu.Items.Add(createTag);
             menu.Items.Add(new Separator());
 
+            var remoteBranches = repo.RemoteBranches();
+            if (remoteBranches.Count > 0) {
+                var trackingIcon = new System.Windows.Shapes.Path();
+                trackingIcon.Style = FindResource("Style.Icon") as Style;
+                trackingIcon.Data = FindResource("Icon.Branch") as Geometry;
+                trackingIcon.VerticalAlignment = VerticalAlignment.Bottom;
+                trackingIcon.Width = 10;
+
+                var currentTrackingIcon = new System.Windows.Shapes.Path();
+                currentTrackingIcon.Style = FindResource("Style.Icon") as Style;
+                currentTrackingIcon.Data = FindResource("Icon.Check") as Geometry;
+                currentTrackingIcon.VerticalAlignment = VerticalAlignment.Center;
+                currentTrackingIcon.Width = 10;
+
+                var tracking = new MenuItem();
+                tracking.Header = "Tracking ...";
+                tracking.Icon = trackingIcon;
+
+                foreach (var b in remoteBranches) {
+                    var target = new MenuItem();
+                    target.Header = b.Name;
+                    if (branch.Upstream == b.FullName) target.Icon = currentTrackingIcon;
+                    target.Click += (o, e) => {
+                        branch.SetUpstream(repo, b.Name);
+                        e.Handled = true;
+                    };
+                    tracking.Items.Add(target);
+                }
+
+                menu.Items.Add(tracking);
+                menu.Items.Add(new Separator());
+            }
+
             var copy = new MenuItem();
             copy.Header = "Copy Branch Name";
             copy.Click += (o, e) => {