From d7c73f6922cb6f2fa256da48148b34f7744a2556 Mon Sep 17 00:00:00 2001
From: Steven Kirk <grokys@gmail.com>
Date: Fri, 7 Aug 2015 01:03:26 +0200
Subject: [PATCH] Expand TreeViewItems with arrow keys.

---
 Perspex.Controls/TreeViewItem.cs | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/Perspex.Controls/TreeViewItem.cs b/Perspex.Controls/TreeViewItem.cs
index 031e9d697e..f2edb63849 100644
--- a/Perspex.Controls/TreeViewItem.cs
+++ b/Perspex.Controls/TreeViewItem.cs
@@ -100,5 +100,30 @@ namespace Perspex.Controls
                 this.treeView = null;
             }
         }
+
+        protected override void OnKeyDown(KeyEventArgs e)
+        {
+            if (!e.Handled)
+            {
+                switch (e.Key)
+                {
+                    case Key.Right:
+                        if (this.Items != null && this.Items.Cast<object>().Any())
+                        {
+                            this.IsExpanded = true;
+                        }
+
+                        e.Handled = true;
+                        break;
+
+                    case Key.Left:
+                        this.IsExpanded = false;
+                        e.Handled = true;
+                        break;
+                }
+            }
+
+            base.OnKeyDown(e);
+        }
     }
 }