SimpleChildWindow does not behave like a ContentControl, Content can only be a Visual

[Mertsch]

v1.4.1

System.InvalidOperationException: 'xxxViewModel' is not a Visual or Visual3D.
   at MS.Internal.Media.VisualTreeUtils.AsVisual(DependencyObject element, Visual& visual, Visual3D& visual3D)
   at System.Windows.Media.VisualTreeHelper.GetChildrenCount(DependencyObject reference)
   at MahApps.Metro.SimpleChildWindow.Utils.TreeHelper.<GetChildObjects>d__4.MoveNext() in d:\projects\git\MahApps.Metro.SimpleChildWindow\src\MahApps.Metro.SimpleChildWindow\Utils\TreeHelper.cs:line 182
   at MahApps.Metro.SimpleChildWindow.Utils.TreeHelper.<FindChildren>d__3`1.MoveNext() in d:\projects\git\MahApps.Metro.SimpleChildWindow\src\MahApps.Metro.SimpleChildWindow\Utils\TreeHelper.cs:line 140
   at MahApps.Metro.SimpleChildWindow.Utils.TreeHelper.<FindChildren>d__3`1.MoveNext() in d:\projects\git\MahApps.Metro.SimpleChildWindow\src\MahApps.Metro.SimpleChildWindow\Utils\TreeHelper.cs:line 149
   at System.Linq.Enumerable.FirstOrDefault[TSource](IEnumerable`1 source, Func`2 predicate)
   at MahApps.Metro.SimpleChildWindow.ChildWindow.TryFocusElement() in d:\projects\git\MahApps.Metro.SimpleChildWindow\src\MahApps.Metro.SimpleChildWindow\ChildWindow.cs:line 692
   at MahApps.Metro.SimpleChildWindow.ChildWindow.<>c__DisplayClass131_0.<IsOpenedChanged>b__0() in d:\projects\git\MahApps.Metro.SimpleChildWindow\src\MahApps.Metro.SimpleChildWindow\ChildWindow.cs:line 659

Workaround

<metroWindow:ChildWindow>
    <ContentPresenter Content="{Binding Path=xxxViewModel, Mode=OneWay}"/>
</metroWindow:ChildWindow>