Avalonia/samples/IntegrationTestApp/Pages/ComboBoxPage.axaml

<UserControl xmlns="https://github.com/avaloniaui"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
             mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
             x:Class="IntegrationTestApp.Pages.ComboBoxPage">
  <StackPanel>
    <ComboBox Name="BasicComboBox">
      <ComboBoxItem>Item 0</ComboBoxItem>
      <ComboBoxItem>Item 1</ComboBoxItem>
    </ComboBox>
    <CheckBox Name="ComboBoxWrapSelection" IsChecked="{Binding #BasicComboBox.WrapSelection}">Wrap Selection</CheckBox>
    <Button Name="ComboBoxSelectionClear" Click="ComboBoxSelectionClear_Click">Clear Selection</Button>
    <Button Name="ComboBoxSelectFirst" Click="ComboBoxSelectFirst_Click">Select First</Button>
  </StackPanel>
</UserControl>