ComboBox Text

When you want to implement a required ComboBox, but don’t want to default the selection, the initial state of the ComboBox is empty.

How to display a nice message like “Please Select a Widget”?

I always start by setting the Text property, then rub my head as to why it isn’t displayed! The reason is that there is two ControlTemplates used by ComboBox; an Editable one and a non-Editable one. Only the Editable template uses the Text property.

Once you know this small tidbit, the rest is easy. Set IsEditable to true, Set IsReadOnly to True and set your text.

<ComboBox Text="Select An Item or Else!" IsEditable="True" IsReadOnly="True">
       <ComboBoxItem Content="Test 1"/>
       <ComboBoxItem Content="Test 2"/>
</ComboBox>

Note: if you are using a custom ItemTemplate, the selected item will not appear correctly. You should then set IsEditable to true in a trigger when there is no SelectedItem.

<Style TargetType="ComboBox">
  <Style.Triggers>
    <Trigger Property="SelectedItem" Value="{x:Null}">
	<Setter Property="IsEditable" Value="True" />
    </Trigger>
  </Style.Triggers>					
</Style>