check if the visual is connected (#2321)

marinkobabic · amaitland · commit 58e705244bef · 2018-03-23T15:01:48.000+10:00
diff --git a/CefSharp.Wpf/ChromiumWebBrowser.cs b/CefSharp.Wpf/ChromiumWebBrowser.cs
@@ -1622,7 +1622,7 @@ private void WindowStateChanged(object sender, EventArgs e)
 
         private void UpdateBrowserScreenLocation()
         {
-            if (source != null)
+            if (source != null && PresentationSource.FromVisual(this) != null)
             {
                 browserScreenLocation = PointToScreen(new Point());
             }

Original file line number	Diff line number	Diff line change
`@@ -1622,7 +1622,7 @@ private void WindowStateChanged(object sender, EventArgs e)`
`1622`	`1622`
`1623`	`1623`	`private void UpdateBrowserScreenLocation()`
`1624`	`1624`	`{`
`1625`		`- if (source != null)`
	`1625`	`+ if (source != null && PresentationSource.FromVisual(this) != null)`
`1626`	`1626`	`{`
`1627`	`1627`	`browserScreenLocation = PointToScreen(new Point());`
`1628`	`1628`	`}`