WPF

<Menu DockPanel.Dock="Top">
        <ComboBox  IsEditable="False" Width="{Binding Path=ActualWidth, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=Menu}}"></ComboBox>
</Menu>

comboBoxProcessList.Width = (Double)((Menu)sender).ActualWidth - 15;

<ribbon:RibbonWindow
    x:Name="window"
    x:Class="MHManager.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:MHManager"
    xmlns:classes="clr-namespace:MHManager.Classes"
    xmlns:controls="clr-namespace:MHManager.Controls"
    xmlns:shared="http://schemas.actiprosoftware.com/winfx/xaml/shared"
    xmlns:ribbon="http://schemas.actiprosoftware.com/winfx/xaml/ribbon"
    xmlns:themes="http://schemas.actiprosoftware.com/winfx/xaml/themes"
	xmlns:editors="http://schemas.actiprosoftware.com/winfx/xaml/editors"    
	xmlns:ribboneditors="http://schemas.actiprosoftware.com/winfx/xaml/ribboneditors"
    xmlns:s="http://www.stemasoft.com/xaml"
    xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"
    xmlns:ComponentModel="clr-namespace:System.ComponentModel;assembly=WindowsBase"
    xmlns:System="clr-namespace:System;assembly=mscorlib"
    ResizeMode="CanResizeWithGrip" 
    ApplicationName="Manufactured Housing Manager"	    
    Icon="Icons/MHManagericon.ico"
    Background="{Binding Background, ElementName=navigationPane}"
    Height="632"
    Width="930" 
    Loaded="window_Loaded" Closed="applicationExitCommand_Execute">

public Chart ChartObject;

//--------------------------------------------------------------------------------
protected void MakePie(List<RepItem> data, string seriesTitle, string yProperty)
{
    DisplayCategories categories = new DisplayCategories();
    foreach (RepItem item in data)
    {
        categories.Add(item.Category);
    }
    System.Collections.ObjectModel.Collection<ResourceDictionary> palette = MakePalette(categories);
    this.ChartObj.Palette = palette;

    PieSeries series = new PieSeries()
    {
        ItemsSource = data,
        Title = seriesTitle,
        DependentValueBinding = new System.Windows.Data.Binding(yProperty),
        IndependentValueBinding = new System.Windows.Data.Binding("Category"),
        TransitionDuration = new TimeSpan(0),
    };
    //Style style = new Style(typeof(PieDataPoint));
    //ControlTemplate template = Application.Current.Resources["PieDataTemplate"] as ControlTemplate;
    //if (template != null)
    //{
    //    SetStyleProperty(style, ColumnDataPoint.TemplateProperty, template);
    //}
    //series.DataPointStyle = style;
    //series.Palette = palette;
    this.ChartObj.Series.Add(series);
}

<ControlTemplate x:Key="PieDataTemplate" TargetType="wtkchart:PieDataPoint">
    <Grid>
        <Path x:Name="Slice"
              Data="{TemplateBinding Geometry}"
              Fill="{TemplateBinding Background}"
              Stroke="{TemplateBinding BorderBrush}">
            <ToolTipService.ToolTip>
                <StackPanel>
                    <ContentControl Content="{Binding Path=Category}" FontSize="12" />
                    <ContentControl Content="{TemplateBinding FormattedDependentValue,
                                              Converter={StaticResource TooltipValueFormatter}}"
                                    FontWeight="Bold" FontSize="14" />
                    <ContentControl Content="{TemplateBinding FormattedRatio}"/>
                </StackPanel>
            </ToolTipService.ToolTip>
        </Path>
    </Grid>
</ControlTemplate>