<RibbonWindow xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:Custom="http://schemas.microsoft.com/winfx/2006/xaml/presentation/ribbon" x:Class="RibbonComboBox.MainWindow" Title="MainWindow" Height="350" Width="525"> <Grid> <Ribbon HorizontalAlignment="Left" VerticalAlignment="Top" Width="517" Height="113" SelectionChanged="Ribbon_SelectionChanged_1"> <RibbonComboBox x:Name="teste" Label="ComboBox"> <ComboBoxItem Content="2"/> <ComboBoxItem Content="3"/> <ComboBoxItem Content="4"/> </RibbonComboBox> </Ribbon> </RibbonWindow>