Eto LinkButton crash when used in RenderContent UI (V6 & V7)

Rhino Developer
1

I find there is a crash occurring (in 6.26.20118.17211, and 7.0.20119.13305, at least when loading a V6-sdk plugin) when using an Eto LinkButton in a RenderContent UI. To repro, put these classes in a test plugin:

[Guid("0182E9AA-8A98-44A2-B0C1-38639C162635")]
[CustomRenderContent(IsElevated = true)]
public class LinkTestMaterial : RenderMaterial
{
    public override string TypeName => "Link Test"; 
    public override string TypeDescription => "Link Test";

    protected override void OnAddUserInterfaceSections()
    {
        AddUserInterfaceSection(new LinkTestUI());
    }
}

public class LinkTestUI : EtoCollapsibleSection
{
    public override Guid PlugInId => TestRenderPlugIn.PlugInId;
    public override LocalizeStringPair Caption => new LocalizeStringPair("Attrs", "Attrs");
    public override int SectionHeight => 50;

    public LinkTestUI()
    {
        Content = new TableLayout { Rows = { new LinkButton { Text = "link" } } };
    }
}

With the plugin loaded, follow these steps:

1. open the Materials panel
2. create a Link Test material
3. click the link in the material's UI
4. create a Plaster material
5. if it does not crash, select the Link Test material and repeat steps 3-5

There are other actions you can use to trigger it after clicking the link, such as clicking the Back button, or saving with the material in the document, re-opening, clicking the link and closing Rhino (need to save/reopen because the close without saving dialog appears to prevent the crash).

Each method may be somewhat intermittent, but will eventually (should be first or second try) crash with the exception message 'System.Windows.Documents.Hyperlink' is not a Visual or Visual3D.' with the top of the stack trace being:

at MS.Internal.Media.VisualTreeUtils.AsVisual(DependencyObject element, Visual& visual, Visual3D& visual3D)
at System.Windows.Media.VisualTreeHelper.GetParent(DependencyObject reference)
at RhinoWindows.Controls.WpfElementHostBase.<>c.<.ctor>b__1_1(Object sender, KeyboardFocusChangedEventArgs e)
at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)