From 7251e9e55bdf7e67c1f482d29843a40577f49eda Mon Sep 17 00:00:00 2001
From: Steven Kirk <steven.kirk@tricycleinc.com>
Date: Sun, 14 Sep 2014 13:29:40 +0200
Subject: [PATCH] Added TreeViewItem.IsExpanded.

---
 Perspex/Controls/StackPanel.cs              |  2 +-
 Perspex/Controls/TreeViewItem.cs            | 13 ++++++++-----
 Perspex/Themes/Default/TreeViewItemStyle.cs |  1 +
 3 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/Perspex/Controls/StackPanel.cs b/Perspex/Controls/StackPanel.cs
index e2114450f9..4ce3d9a9ac 100644
--- a/Perspex/Controls/StackPanel.cs
+++ b/Perspex/Controls/StackPanel.cs
@@ -107,7 +107,7 @@ namespace Perspex.Controls
                 arrangedWidth = 0;
             }
 
-            foreach (Control child in this.Children)
+            foreach (Control child in this.Children.Where(x => x.DesiredSize.HasValue))
             {
                 double childWidth = child.DesiredSize.Value.Width;
                 double childHeight = child.DesiredSize.Value.Height;
diff --git a/Perspex/Controls/TreeViewItem.cs b/Perspex/Controls/TreeViewItem.cs
index 6c1a841c17..1ad0a27dd2 100644
--- a/Perspex/Controls/TreeViewItem.cs
+++ b/Perspex/Controls/TreeViewItem.cs
@@ -6,12 +6,15 @@
 
 namespace Perspex.Controls
 {
-    using System;
-    using System.Collections;
-    using System.Linq;
-    using System.Reactive.Linq;
-
     public class TreeViewItem : HeaderedItemsControl
     {
+        public static readonly PerspexProperty<bool> IsExpandedProperty =
+            PerspexProperty.Register<TreeViewItem, bool>("IsExpanded");
+
+        public bool IsExpanded
+        {
+            get { return this.GetValue(IsExpandedProperty); }
+            set { this.SetValue(IsExpandedProperty, value); }
+        }
     }
 }
diff --git a/Perspex/Themes/Default/TreeViewItemStyle.cs b/Perspex/Themes/Default/TreeViewItemStyle.cs
index 030f0a81b8..2395af85a3 100644
--- a/Perspex/Themes/Default/TreeViewItemStyle.cs
+++ b/Perspex/Themes/Default/TreeViewItemStyle.cs
@@ -61,6 +61,7 @@ namespace Perspex.Themes.Default
                         Margin = new Thickness(24, 0, 0, 0),
                         [~ItemsPresenter.ItemsProperty] = control[~TreeViewItem.ItemsProperty],
                         [~ItemsPresenter.ItemsPanelProperty] = control[~TreeViewItem.ItemsPanelProperty],
+                        [~ItemsPresenter.IsVisibleProperty] = control[~TreeViewItem.IsExpandedProperty],
                     }
                 }
             };