Binding only part of the margin property of WPF control

I have this:

<TabControl Margin="0,24,0,0">...</TabControl>

I want to bind only the "Top" part of the TabControl, which intuitively I would do it this way:

<TabControl Margin="0,{Binding ElementName=TheMenu, Path=Height},0,0">
 ...
</TabControl>

How do I do it ?

Have you tried using a converter like this?

in VB.Net

Public Class MarginConverter
  Implements IValueConverter

  Public Function Convert(ByVal value As Object, ByVal targetType As System.Type, ByVal parameter As Object, ByVal culture As System.Globalization.CultureInfo) As Object Implements System.Windows.Data.IValueConverter.Convert
    Return New Thickness(0, CDbl(value), 0, 0)
  End Function

  Public Function ConvertBack(ByVal value As Object, ByVal targetType As System.Type, ByVal parameter As Object, ByVal culture As System.Globalization.CultureInfo) As Object Implements System.Windows.Data.IValueConverter.ConvertBack
    Return Nothing
  End Function
End Class

Or in C#

public class MarginConverter : IValueConverter
{

	public object Convert(object value, System.Type targetType, object parameter, System.Globalization.CultureInfo culture)
	{
		return new Thickness(0, System.Convert.ToDouble(value), 0, 0);
	}

	public object ConvertBack(object value, System.Type targetType, object parameter, System.Globalization.CultureInfo culture)
	{
		return null;
	}
}

XAML

<Window.Resources>
    <local:MarginConverter x:Key="marginConverter"></local:MarginConverter>
</Window.Resources>
<Grid>
    <StackPanel>
        <Slider Name="Slider1"></Slider>
        <TabControl Name="TabControl" Margin="{Binding ElementName=Slider1, Path=Value, Converter={StaticResource marginConverter}}">
            <Button>Some content</Button>
        </TabControl>
    </StackPanel>
</Grid>

Edit:
Using a MultiConverter

It is also possible to get all four values during run-time and use a MultiValueConverter. The Top-Property of the Thickness-Object is not a Dependency-Object, therefor you can't define a binding to it (unless your source is not a Dependency-Object).

XAML

<Window.Resources>
    <local:MarginConverter x:Key="marginConverter"></local:MarginConverter>
    <local:MultiMarginConverter x:Key="multiMarginConverter"></local:MultiMarginConverter>
</Window.Resources>
<Grid>
    <StackPanel>
        <Slider Name="Slider1"></Slider>
        <Slider Name="Slider2"></Slider>
        <Slider Name="Slider3"></Slider>
        <Slider Name="Slider4"></Slider>
        <TabControl Name="TabControl">
            <TabControl.Margin>
                <MultiBinding Converter="{StaticResource multiMarginConverter}">
                    <Binding ElementName="Slider1" Path="Value"></Binding>
                    <Binding ElementName="Slider2" Path="Value"></Binding>
                    <Binding ElementName="Slider3" Path="Value"></Binding>
                    <Binding ElementName="Slider4" Path="Value"></Binding>
                </MultiBinding>
            </TabControl.Margin>
            <Button>Some content</Button>
        </TabControl>
    </StackPanel>
</Grid>

... and c#

  class MultiMarginConverter : IMultiValueConverter
  {
    public object Convert(object[] values, System.Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
      return new Thickness(System.Convert.ToDouble(values[0]),
                           System.Convert.ToDouble(values[1]),
                           System.Convert.ToDouble(values[2]),
                           System.Convert.ToDouble(values[3]));
    }

    public object[] ConvertBack(object value, System.Type[] targetType, object parameter, System.Globalization.CultureInfo culture)
    {
      return null;
    }
  }

Edit(2) Reverse-Binding:
I'm not sure if this will make you happy. In my humble opinion I would try to avoid this, but ok... If your source is a Dependency-Property, you can bind this to the Margin:

<Slider Name="Slider5" Minimum="-99" Maximum="0" Value="{Binding ElementName=TabControl, Path=Margin.Top, Mode=OneWayToSource}"></Slider>

But I've got some effects with this.
The trick is, that you do not bind a part of the Margin of your TabControl to "something else", but bind "something else" to the Margin of your TabControl and specify Binding-Mode OneWayToSource.

Actually Margin property of a control is of Thickness Type. So we can bind it to Property if type Thickness.

 public Thickness LeftMargin { get; set; }

and You can set a part of a Thickness object too. Like -

 LeftMargin = new Thickness(20,0,0,0);

and in Xaml we can bind this property directly to margin property of any element..like this..

 <TextBlock Text="Some Text"  Margin="{Binding LeftMargin}"  />

You could try something like this answer from another question.

The solution uses an attached property that allows for XAML like the following:

<Button ap:MoreProps.MarginRight="10" />

The attached property is also backed by a DependencyObject so data binding will work.

I have used this workaround for left margin only with StackPanel. Benefit is that you don't need any Converter.

<DockPanel VerticalAlignment="Top">
  <TextBlock Name="tbkFulltextCaption"
             Text="Static Caption:"
             DockPanel.Dock="Left" />
  <StackPanel Orientation="Horizontal"
              DockPanel.Dock="Bottom">
      <FrameworkElement Name="feLeftMargin"
                        Width="{Binding Width, ElementName=tbkFulltextCaption, Mode=OneWay}" />
      <TextBlock Text="(some text with margin of tbkFulltextCaption.Width)"
                 Name="tbkUnderNonsense" 
                 FontSize="8"                                       
                 Foreground="Gray">
      </TextBlock>
  </StackPanel>
  <TextBox Name="tbFulltextSearch" />
</DockPanel>

preview

From your code, I figure that your menu and tabControl may overlap, so you want to use margin to separate them. I feel this practice like two Column CSS Layout.

Back to the point, I think you can apply TranslateFransform to TabControl.RenderTransform. You can bind Y property.

To expand on Ioop's method of making a property to control margin instead of a converter if you aren't attaching to another WPF element:

Create 4 standard properties and a readonly property, like so-

Public Class CustomMargin
	Implements INotifyPropertyChanged

	Private _Left As Double
	Private _Right As Double
	Private _Up As Double
	Private _Down As Double

    Public Sub New()
      _Up = 0
      _Down = 0
      _Left = 0
      _Right = 0
    End Sub

    Public Sub New(Vertical as Double, Horizontal as Double)
      _Up = Vertical
      _Down = Vertical
      _Left = Horizontal
      _Right = Horizontal
    End Sub

    Public Sub New(Left as Double, Up as Double, Right as Double, Down as Double)
      _Up = Up
      _Down = Down
      _Left = Left
      _Right = Right
    End Sub

	Public Property Left As Double
		Get
			Return _Left
		End Get
		Set(value As Double)
			_Left = value
			OnPropertyChanged(New PropertyChangedEventArgs("MyMargin"))
		End Set
	End Property

	Public Property Right As Double
		Get
			Return _Right
		End Get
		Set(value As Double)
			_Right = value
			OnPropertyChanged(New PropertyChangedEventArgs("MyMargin"))
		End Set
	End Property

	Public Property Up As Double
		Get
			Return _Up
		End Get
		Set(value As Double)
			_Up = value
			OnPropertyChanged(New PropertyChangedEventArgs("MyMargin"))
		End Set
	End Property

	Public Property Down As Double
		Get
			Return _Down
		End Get
		Set(value As Double)
			_Down = value
			OnPropertyChanged(New PropertyChangedEventArgs("MyMargin"))
		End Set
	End Property

	Public ReadOnly Property MyMargin As Thickness
		Get
			Return New Thickness(Left, Up, Right, Down)
		End Get
	End Property

	Public Event PropertyChanged As PropertyChangedEventHandler Implements INotifyPropertyChanged.PropertyChanged

	Public Sub OnPropertyChanged(ByVal e As PropertyChangedEventArgs)
		If Not PropertyChangedEvent Is Nothing Then
			RaiseEvent PropertyChanged(Me, e)
		End If
	End Sub
End Class

Then you just have to add the XAML-

<Label x:Name="MyLabel" Margin="{Binding Path=MyMargin, FallbackValue=0 0 0 0, Mode=OneWay}"/>

Then on the code behind on the WPF window-

Private _NewMargin as New CustomMargin

Public Sub New()
  InitializeComponent()
  MyLabel.DataContext = _NewMargin
End Sub

From there you can use whatever control you desire to change all 4 margins separately and the Class is reusable for other controls.

Ok it is old, but I was searching for a nicer way:

<TabControl>
    <TabControl.Margin>
        <Thickness Top="{Binding ElementName=TheMenu, Path=Height}" />
     </TabControl.Margin>
</TabControl>