WPF XamComboEditor/ComboEditorTool - Setting default text

Question

Hi

I'm trying to add some default text to combo boxes that will show when there is no item selected. I'm using a style to acheive this which works great when the combo is first loaded.

<Style TargetType="{x:Type igRibbon:ComboEditorTool}" x:Key="PleaseSelect">
<Style.Triggers>
<Trigger Property="SelectedIndex" Value="-1">
<Setter Property="Text" Value="Please Select" />
</Trigger>
</Style.Triggers>
</Style>

<igRibbon:ComboEditorTool Style="{StaticResource PleaseSelect}" 
ItemsSource="{Binding MyItems}" SelectedItem="{Binding MySelectedItem }" />

But when the combo's selected item is reset (by setting it to null, which sets the SelectedIndex to -1) it fails to display the default text (even though the the trigger does fire), what could be the reason for this? Is there a better way to reset the selected item?

Cheers

Answer 1

I'm not familiar with the Infragistics suite, but I suspect it's the same thing as with regular combo boxes: since you have a binding on SelectedItem, the Text cannot be set to an item that blatantly disobeys that binding; the Text IS a representation of the SelectedItem. If the SelectedItem is null, then the Text must also be a representation of null.

I'm guessing (didn't try it and I may be just plain wrong) you could probably accomplish this with an IValueConverter that returns a custom string when the passed object is null (and returns the object unchanged otherwise), set on the SelectedItem binding.