wpf menu tab stop strange behaviour

I've just been cleaning u开发者_如何转开发p my program and I was checking how the tabs worked when I came across this very strange behaviour. My Main menu items were included in the tab order. Thinking that was strange I set their IsTabStop property to false, and ran it again.

They were no longer in my tab order but when I pressed ALT to activate the menu I could no longer use the arrow keys to navigate between the items.

Is there a way around this and make the menu act like a normal old school menu?

Here's how to exclude your menus from the tab order using KeyboardNavigation.TabNavigation:

<DockPanel>
    <Menu DockPanel.Dock="Top">
        <MenuItem Header="_File">
            <MenuItem Header="Open"/>
            <MenuItem Header="E_xit"/>
        </MenuItem>
    </Menu>
    <StackPanel KeyboardNavigation.TabNavigation="Cycle">
        <TextBox Text=""/>
        <TextBox Text=""/>
    </StackPanel>
</DockPanel>