From 7e3082dcecde6b6f3fc0573b06fbf34bd1b8bb67 Mon Sep 17 00:00:00 2001
From: Steven Kirk <grokys@gmail.com>
Date: Wed, 6 Jul 2016 00:08:36 +0200
Subject: [PATCH] Prevent stack overflow in focus code.

When a focus scope had null as its focused element, a stack overflow was
occurring. Fixes #577.
---
 src/Avalonia.Input/FocusManager.cs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/Avalonia.Input/FocusManager.cs b/src/Avalonia.Input/FocusManager.cs
index 37026d16f5..e5cc5a8557 100644
--- a/src/Avalonia.Input/FocusManager.cs
+++ b/src/Avalonia.Input/FocusManager.cs
@@ -79,7 +79,7 @@ namespace Avalonia.Input
                 {
                     IInputElement element;
 
-                    if (_focusScopes.TryGetValue(scope, out element))
+                    if (_focusScopes.TryGetValue(scope, out element) && element != null)
                     {
                         Focus(element, method);
                         return;