WPF Combobox: Different template in textbox and drop-downlist

Question

This is my combo-box.

Answer 1

You could override the ComboBox and change the SelectionBoxItemTemplate directly.

public class SelectionComboBox : ComboBox
{
    #region Properties

    #region Dependency Properties
    public DataTemplate AltSelectionBoxItemTemplate
    {
        get { return (DataTemplate)GetValue(AltSelectionBoxItemTemplateProperty); }
        set { SetValue(AltSelectionBoxItemTemplateProperty, value); }
    }

    public static readonly DependencyProperty AltSelectionBoxItemTemplateProperty =
        DependencyProperty.Register("AltSelectionBoxItemTemplate", typeof(DataTemplate), typeof(SelectionComboBox), new UIPropertyMetadata(null, (s, e) =>
        {
            // For new changes...
            if ((s is SelectionComboBox) && ((SelectionComboBox)s).Presenter != null && (e.NewValue is DataTemplate))
                ((SelectionComboBox)s).Presenter.ContentTemplate = (DataTemplate)e.NewValue;

            // Set the new value
            ((SelectionComboBox)s).AltSelectionBoxItemTemplate = (DataTemplate)e.NewValue;
        }));
    #endregion

    #region Internals

    #region Elements
    ContentPresenter Presenter { get; set; }
    #endregion

    #endregion

    #endregion

    #region Constructors
    #endregion

    #region Methods

    #region Overrides
    public override void OnApplyTemplate()
    {
        base.OnApplyTemplate();

        Presenter = this.GetTemplateChild("contentPresenter") as ContentPresenter;

        // Directly Set the selected item template
        if (AltSelectionBoxItemTemplate != null) Presenter.ContentTemplate = AltSelectionBoxItemTemplate;
    }
    #endregion

    #endregion

}

Once you define the control, you could style it.