Expression Blend and Sample data for Dictionary in WPF application

I have a WPF app which I am using Blend to style.

One of my view models is of the type:

public Dictionary<DateTime, ObservableCollection<MyViewModel>> TimesAndEvents

But when I try to create some sample data in Expression Blend it simply doesnt create the XAML for this property.

Can you create a data type like this in XAML? The non-design time support is killing my productivity.