From 9f8d9ed1cb523010d0b0c1f085a528275521440e Mon Sep 17 00:00:00 2001
From: Steven Kirk <grokys@gmail.com>
Date: Fri, 25 Mar 2016 18:45:22 +0100
Subject: [PATCH] Use pointer position in Popup if can't find target.

If a rooted placement target could not be found, use the current pointer
position as the position of the popup.
---
 src/Perspex.Controls/Primitives/Popup.cs | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/Perspex.Controls/Primitives/Popup.cs b/src/Perspex.Controls/Primitives/Popup.cs
index e253d81912..3b16b349c2 100644
--- a/src/Perspex.Controls/Primitives/Popup.cs
+++ b/src/Perspex.Controls/Primitives/Popup.cs
@@ -276,12 +276,18 @@ namespace Perspex.Controls.Primitives
         protected virtual Point GetPosition()
         {
             var zero = default(Point);
+            var mode = PlacementMode;
             var target = PlacementTarget ?? this.GetVisualParent<Control>();
 
-            switch (PlacementMode)
+            if (target?.GetVisualRoot() == null)
+            {
+                mode = PlacementMode.Pointer;
+            }
+
+            switch (mode)
             {
                 case PlacementMode.Pointer:
-                    return MouseDevice.Instance.Position;
+                    return MouseDevice.Instance?.Position ?? default(Point);
 
                 case PlacementMode.Bottom:
                     return target?.PointToScreen(new Point(0, target.Bounds.Height)) ?? zero;