There is no standard automatic full control in WPF. You can google for third parties. But there is one very simple way to create a simplified automatic full control by slightly adjusting the editable ComboBox template:
<ComboBox IsEditable="True"> <ComboBox.Template> <ControlTemplate TargetType="{x:Type ComboBox}"> <TextBox x:Name="PART_EditableTextBox" /> </ControlTemplate> </ComboBox.Template> <TextBlock Text="Hello"/> <TextBlock Text="World"/> </ComboBox>
source share