Databound TreeviewItem does not respond to changes when inside Mahapps window. (Sample Project attached)

Hello,

i have a TreeView control which has TreeviewItems bound to a viewmodel. In a standard Window the tree reflects changes to IsVisible, IsExpanded and IsSelected properties. But this does not work as soon as tree is in a mahapps window.

I created a solution that directly shows the problem, so that you can quickly see what this issue is about.

http://portalvhdstlvf6zph5075c.blob.core.windows.net/exchange/TreeViewWpfApplication.7z

[punker76]

@pothmann there are 2 points in this issue:

1. MahApps should not set the MetroTreeViewItem style as the ItemContainerStyle, this is fixed with 6cc298b
2. you should inherit the TreeViewItem style

        <Style TargetType="{x:Type TreeViewItem}" BasedOn="{StaticResource {x:Type TreeViewItem}}">
            <Setter Property="Visibility"
                    Value="{Binding IsVisible, Converter={StaticResource BooleanToVisibilityConverter}}" />
            <Setter Property="IsExpanded"
                    Value="{Binding IsExpanded}" />
            <Setter Property="IsSelected"
                    Value="{Binding IsSelected}" />

        </Style>