WPF Combobox: Different template in textbox and drop-downlist

Question

This is my combo-box.

Answer 1

Instead of using the read-only SelectionBoxItemTemplate property I created a new (attached, writable) property and used that one in my style. I also added a trigger to my style to not break all the comboboxes that are not using my new attached property...

Use it like this:

    
        
            ... Template for the selection box ...
        
    
    
        
            ... Template for the popup ...
        
    

You just have to add this class to your project:

public class ComboBoxSelectionBoxAltTemplateBehaviour
{
    public static readonly DependencyProperty SelectionBoxAltTemplateProperty = DependencyProperty.RegisterAttached(
        "SelectionBoxAltTemplate", typeof (DataTemplate), typeof (ComboBoxSelectionBoxAltTemplateBehaviour), new PropertyMetadata(default(DataTemplate)));

    public static void SetSelectionBoxAltTemplate(DependencyObject element, DataTemplate value)
    {
        element.SetValue(SelectionBoxAltTemplateProperty, value);
    }

    public static DataTemplate GetSelectionBoxAltTemplate(DependencyObject element)
    {
        return (DataTemplate) element.GetValue(SelectionBoxAltTemplateProperty);
    }

}

and change your ComboBox style to use the SelectionBoxAltTemplate attached property if set (or because I could not set a trigger to "not null", I set it back to the default SelectionBoxItemTemplate if the attached one is null):

The ContentPresenter inside the ControlTemplate of the ComboBox Style:

And the Trigger to provide backwards compatibility to ComboBoxed without the attached Property:

    
        
    
    ...

Full Style:

However this might not work with ItemTemplateSelctors, only with one single template - but you could easily add an attached property "SelectionBoxAltTemplateSelector" which provides the selector and passes that one to the style.