Horizontal right alignment is not working correctly in WPF

Question

For reference, I am including Horizontal alignment question which is even referenced in the comments of our legacy codebase.

The code is in a .xaml file, the relevant part is:

<MenuItem Header="Help" HorizontalAlignment="Right">
    <MenuItem Header="About"></MenuItem>
</MenuItem>

This code builds. However, when debugging the code, what I see is

I would like to correct this, so that one can see the entire word "Help".

Is there an offset-mechanism in the WPF XAML file or some other way to do this?

NOTE: I have found my own 'hack' that seems to fix the problem, simply adding spaces after Help within the quote-marks works and makes it display better, but surely there must be a more elegant way:

<MenuItem Header ="Help       " HorizontalAlignment="Right">
    <MenuItem Header="About" CommandParameter="Help_About"></MenuItem>
</MenuItem>

Per request, this is the entire context of the menu, some of the items have been obfuscated since they may be proprietary:

<Menu xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Name="appFrameworkMainMenu" 
    Grid.Row="0">


    <Menu.ItemsPanel>
        <ItemsPanelTemplate>
            <DockPanel HorizontalAlignment="Stretch"/>
        </ItemsPanelTemplate>
    </Menu.ItemsPanel>

    <MenuItem Name="Name1" Header="File">

        <MenuItem  Header="MenuItem1a" ></MenuItem>
        <Separator />

        <MenuItem  Header="Exit Application"  ></MenuItem>

    </MenuItem>

    <MenuItem Name="Name2" Header="File">

        <MenuItem  Header="MenuItem2a" ></MenuItem>
        <MenuItem  Header="MenuItem2b" ></MenuItem> 
    </MenuItem>

    <MenuItem Name="Name3" Header="File">

        <MenuItem  Header="MenuItem3a" ></MenuItem>
        <MenuItem  Header="MenuItem3b" ></MenuItem> 
    </MenuItem>

   <!-- align right:  http://stackoverflow.com/questions/3023638/how-do-i-right-align-the-help-menu-item-in-wpf  -->

    <MenuItem Header ="Help       "  HorizontalAlignment="Right" >
        <MenuItem  Header="About"    ></MenuItem>
    </MenuItem>

</Menu>

Then, per comment suggestion, I tried a simple text block and it appears to be on the left, whether or not the HorizontalAligment = "Right" directive is in the code:

<TextBlock  HorizontalAlignment="Right" >Help me </TextBlock>

Answer 1

Put your Menu inside DockPanel instead:

<Window x:Class="WpfTutorialSamples.Common_interface_controls.MenuSample"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MenuSample" Height="600" Width="800">
    <DockPanel>
        <Menu DockPanel.Dock="Top" Name="appFrameworkMainMenu">
            <Menu.ItemsPanel>
                <ItemsPanelTemplate>
                    <DockPanel HorizontalAlignment="Stretch"/>
                </ItemsPanelTemplate>
            </Menu.ItemsPanel>
            <MenuItem Name="Name1" Header="File">
                <MenuItem Header="MenuItem1a" />
                <Separator />
                <MenuItem Header="Exit Application" />
            </MenuItem>
            <MenuItem Name="Name2" Header="File">
                <MenuItem Header="MenuItem2a" />
                <MenuItem Header="MenuItem2b" />
            </MenuItem>
            <MenuItem Name="Name3" Header="File">
                <MenuItem Header="MenuItem3a" />
                <MenuItem Header="MenuItem3b" />
            </MenuItem>
            <MenuItem Header ="Help" HorizontalAlignment="Right">
                <MenuItem Header="About" />
            </MenuItem>
        </Menu>
        <Grid ....>
    </DockPanel>
</Window>

Disclaimer: I haven't tested this code, but I'm pretty sure it should help you to solve this issue.