ContextMenu style produces weird Binding errors without using any Binding

Question

I have a very strange problem:

I use this XAML-Style:

<Style TargetType="ContextMenu">
    <Setter Property="ItemsSource">
        <Setter.Value>
            <CompositeCollection>
                <MenuItem Header="Test"/>
            </CompositeCollection>
        </Setter.Value>
     </Setter>
</Style>

It works BUT my Console has the following errors:

System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.ItemsControl', AncestorLevel='1''. BindingExpression:Path=HorizontalContentAlignment; DataItem=null; target element is 'MenuItem' (Name=''); target property is 'HorizontalContentAlignment' (type 'HorizontalAlignment')
System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.ItemsControl', AncestorLevel='1''. BindingExpression:Path=VerticalContentAlignment; DataItem=null; target element is 'MenuItem' (Name=''); target property is 'VerticalContentAlignment' (type 'VerticalAlignment')
System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.ItemsControl', AncestorLevel='1''. BindingExpression:Path=HorizontalContentAlignment; DataItem=null; target element is 'MenuItem' (Name=''); target property is 'HorizontalContentAlignment' (type 'HorizontalAlignment')
System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.ItemsControl', AncestorLevel='1''. BindingExpression:Path=VerticalContentAlignment; DataItem=null; target element is 'MenuItem' (Name=''); target property is 'VerticalContentAlignment' (type 'VerticalAlignment')
System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.ItemsControl', AncestorLevel='1''. BindingExpression:Path=HorizontalContentAlignment; DataItem=null; target element is 'MenuItem' (Name=''); target property is 'HorizontalContentAlignment' (type 'HorizontalAlignment')
System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.ItemsControl', AncestorLevel='1''. BindingExpression:Path=VerticalContentAlignment; DataItem=null; target element is 'MenuItem' (Name=''); target property is 'VerticalContentAlignment' (type 'VerticalAlignment')
System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.ItemsControl', AncestorLevel='1''. BindingExpression:Path=HorizontalContentAlignment; DataItem=null; target element is 'MenuItem' (Name=''); target property is 'HorizontalContentAlignment' (type 'HorizontalAlignment')
System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.ItemsControl', AncestorLevel='1''. BindingExpression:Path=VerticalContentAlignment; DataItem=null; target element is 'MenuItem' (Name=''); target property is 'VerticalContentAlignment' (type 'VerticalAlignment')

Can anyone explain me what produces the errors and how to get rid of them?

Can you create a small independent sample and share that. Because this is a generic context menu and it can be applied to anything. The issue can be with any other control in your xaml — Versatile, May 28 '15 at 13:38

score 5 · Accepted Answer · edited May 23 '17 at 12:25

5

It is a known problem in WPF where the default style of MenuItem tries to bind to the HorizontalContentAlignment and VerticalContentAlignment of the ItemsControl.

You should be able to bypass these errors by overriding the two properties:

   <Style TargetType="MenuItem">
    <Setter Property="HorizontalContentAlignment" Value="Left"/>
    <Setter Property="VerticalContentAlignment" Value="Center"/>
   </Style>

More information on this issue in these posts:

ListBox with Grid as ItemsPanelTemplate produces weird binding errors

MenuItem added programmatically causes Binding error

edited May 23 '17 at 12:25

Community

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answered May 28 '15 at 13:41

Bruno V

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Thank you! Could this also be a reason for closing the ContextMenu immediately after a certain action? (Before this action it works perfekt!) – MisterPresident May 29 '15 at 11:17

ContextMenu style produces weird Binding errors without using any Binding

1 Answers1