MenuItem databinding - wpf

Question

I've been puzzling over this for a day or so with no luck - I'm probably missing something obvious. Basically, I have a context menu with two items. One is statically declared, and bound to a command. The other has no command of its own, but binds to a collection of viewmodels. So visually the menu should look something like:
Delete
Add
Item 1
Item 2
Where the items vary depending on the thing the context menu was bound to. Originally I had something like this:
<ContextMenu x:Key="itemContextMenu">
<MenuItem Header="_Delete"
Command="{Binding DeleteCommand}" />
<MenuItem Header="_Add" DataContext=""
ItemsSource="{Binding AvailableTypes}">
<MenuItem.ItemTemplate>
<DataTemplate>
<MenuItem Header="{Binding Path=ItemType.Name}"
Command="{Binding Path=AddItemCommand, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=Grid}}"
CommandParameter="{Binding}" />
</DataTemplate>
</MenuItem.ItemTemplate>
</MenuItem>
</ContextMenu>
Which works, but gives me the nested MenuItems others have experienced. Based on a couple threads here on stackoverflow, I then tried this:
<ContextMenu x:Key="itemContextMenu">
<MenuItem Header="_Delete"
Command="{Binding DeleteCommand}" />
<MenuItem Header="_Add"
ItemsSource="{Binding AvailableTypes}">
<MenuItem.ItemContainerStyle>
<Style TargetType="MenuItem">
<Setter Property="Header"
Value="{Binding Path=ItemType.Name}" />
<Setter Property="Command"
Value="{Binding Path=AddItemCommand, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=Grid}}" />
<Setter Property="CommandParameter"
Value="{Binding}" />
</Style>
</MenuItem.ItemContainerStyle>
</MenuItem>
</ContextMenu>
However, when I do that my bindings all fail with errors like:
BindingExpression path error: 'ItemType' property not found on 'object' ''String'
BindingExpression path error: 'AddItemCommand' property not found on 'object' ''Grid'
To me that says that the DataContext is getting lost when I use the ItemContainerStyle. What am I missing?
edit:
I think I had some red herrings in here, so I've simplified the examples further to try and narrow down the problem.
Working but screwy layout-wise:
<ContextMenu x:Key="itemContextMenu">
<MenuItem Header="_Delete" />
<MenuItem Header="_Add" DataContext=""
ItemsSource="{Binding AvailableTypes}">
<MenuItem.ItemTemplate>
<DataTemplate>
<MenuItem Header="{Binding Path=ItemType.Name}" />
</DataTemplate>
</MenuItem.ItemTemplate>
</MenuItem>
</ContextMenu>
Non-working with a BindingExpression error:
<ContextMenu x:Key="itemContextMenu">
<MenuItem Header="_Delete" />
<MenuItem Header="_Add"
ItemsSource="{Binding AvailableTypes}">
<MenuItem.ItemContainerStyle>
<Style TargetType="MenuItem">
<Setter Property="Header"
Value="{Binding Path=ItemType.Name}" />
</Style>
</MenuItem.ItemContainerStyle>
</MenuItem>
</ContextMenu>

Answer 1

Apparently this is a bug in 3.5. I upgraded my project to 4.0, and now everything works as expected.