WPF Popup MenuItem stays highlighted when using arrow keys

After opening a Popup menu programatically, if the user uses up and down arrow keys to move through the menu, menu items get highlighted and they never get unhighlighted. What can I do so that after the user presses the down arrow, the previously highlighted menuitem becomes unhighlighted?

This happens with a very simple Popup menu:

<Grid>
    <Button x:Name="Button1" Content="Open Menu" 
            Click="OnPopupMenuButton_Click"
            Height="23" HorizontalAlignment="Left" Margin="69,12,0,0" VerticalAlignment="Top" Width="75" />

    <Popup x:Name="MyPopupMenu" StaysOpen="False" >
        <StackPanel Orientation="Vertical" Background="White" Margin="0">
            <MenuItem x:Name="xAimee" Header="Aimee" Margin="0,2,0,0" />
            <MenuItem x:Name="xBarbara" Header="Barbara" />
            <MenuItem x:Name="xCar开发者_运维百科ol" Header="Carol" />
            <Separator x:Name="xSeparator1" Margin="0,2,2,2"/>
            <MenuItem x:Name="xDana" Header="Dana" />
            <MenuItem x:Name="xElizabeth" Header="Elizabeth" />
        </StackPanel>
    </Popup>
</Grid>

Here is how the Popup gets opened:

private void OnPopupMenuButton_Click(object sender, System.Windows.RoutedEventArgs e)
{
    Button button = sender as Button;

    MyPopupMenu.PlacementTarget = button;
    MyPopupMenu.Placement = PlacementMode.Mouse;
    MyPopupMenu.IsOpen = true;
    MyPopupMenu.StaysOpen = false;
}

I have been following up on archer's suggestion, but I had a few issues. First, I did not want the menu to open on a right-click, partly because I just didn't want it to open on a right-click and partly because I actually need to use PlacementMode.Top, and the context menu kept opening in the standard context-menu place (to the side and down).

So in the end, I did end up using a Context Menu, but I did a couple of special things. First, in the Window constructor, I set the button's ContextMenu to null, to prevent it from opening when right-clicked. Then when the user left-clicks, I programmatically set the ContextMenu to the one that I created in the xaml file. When the menu closes, I set the button's ContextMenu back to null. I tried manipulating the ContextMenu visibility instead, but that did not seem to work as well as setting it to null and back to an object.

Here is the final xaml, not too different from the question exception that I am handling the Closed event for the ContextMenu.

<Button x:Name="xOpenContextMenuButton" Content = "Open Menu" 
    Click="OnContextMenuButton_Click"
    HorizontalAlignment="Right" VerticalAlignment="Bottom" 
    Width="80" Margin="0,0,36,8" Height="23">

    <Button.ContextMenu>
        <ContextMenu x:Name="xContextMenu" Closed="OnContextMenu_Closed">
            <MenuItem x:Name="xAimee" Header="Aimee" />
            <MenuItem x:Name="xBarbara" Header="Barbara" />
            <MenuItem x:Name="xCarol" Header="Carol" />
            <Separator x:Name="xSeparator1" Margin="0,2,2,2" />
            <MenuItem x:Name="xDana" Header="Dana" />
            <MenuItem x:Name="xElizabeth" Header="Elizabeth" />
        </ContextMenu>
    </Button.ContextMenu>
</Button>

Here is the code-behind, which changed a lot:

public MainWindow()
{
    InitializeComponent();

    xOpenContextMenuButton.ContextMenu = null;
}

private void OnContextMenuButton_Click(object sender, System.Windows.RoutedEventArgs e)
{
    xOpenContextMenuButton.ContextMenu = xContextMenu;

    xContextMenu.PlacementTarget = xOpenContextMenuButton;
    xContextMenu.Placement = PlacementMode.Top;

    xContextMenu.IsOpen = true;
    xContextMenu.StaysOpen = false;
}

private void OnContextMenu_Closed(object sender, RoutedEventArgs e)
{
    xOpenContextMenuButton.ContextMenu = null;
}

Once again, thanks to archer, because I didn't realize that using Popup was not the normal way to create a popup menu in WPF. I think the root cause of the problem is, a Popup can contain anything -- a label, another button, etc. Popup isn't necessarily expecting embedded MenuItems, so it isn't smart enough to understand that it should switch between my menu items when using the arrow keys. But a ContextMenu expects to have MenuItems in it so it knows how to switch between them.