SelectionBoxTemplate allows to choose only one template. What is items collection consists of object of different types? My traditional solution has a set of templates with names {TYPENAME}_ComboCollapsed and {TYPENAME}_ComboExpaned. Its easy to find proper data template using ItemTemplateSelector.
publicoverrideDataTemplate SelectTemplate(objectitem, DependencyObject container){ if(container == null) { // Telerik ??? returnnull; } var presenter = container asContentPresenter; if(presenter == null) { // ??? returnnull; } var templateName = presenter.TemplatedParent isComboBox ? "Collapsed" : "Expanded"; templateName = string.Format("{0}_Combo{1}", item.GetType().Name, templateName); returnGetTemplateByName(templateName, presenter);}