Default value for the 'Options' property cannot be bound to a specific thread

Question

I find that when I change a class from

public class MarkdownEditorOptions : ObservableObject

to

public class MarkdownEditorOptions : INotifyPropertyChanged, DependencyObject

as I wanted to use dependency properties, I get the error

Default value for the 'Options' property cannot be bound to a specific thread. ...\Views\ShellView.xaml

Options is declared as a dependency property on ShellViewModel

public MarkdownEditorOptions Options
{
    get { return (MarkdownEditorOptions)GetValue(OptionsProperty); }
    set { SetValue(OptionsProperty, value); }
}

public static readonly DependencyProperty OptionsProperty =
    DependencyProperty.Register("Options", typeof(MarkdownEditorOptions), typeof(ShellViewModel), new UIPropertyMetadata(new MarkdownEditorOptions()));

whats wrong?

Answer 1

See these questions

• Why Would a Dependency-Property Implementation Crash My Application When I Provide a Default Value?
• Attached Property: 'System.TypeInitializationException' when setting default value

Your Dependency property is not thread safe, meaning that it doesn't inherit from System.Windows.Freezable.
Change DependencyObject to Freezable and it'll work since Freezable derives from DependencyObject.