In my MVVM project I use IDataErrorInfo to propagate exception text to the UI using standard WPF Validation mechanism. With XamComboEditor 2013.1 setting Validation.ErrorTemplate to a customized control template has no effect. In this case, on validation error Control Template should show red border around the control and exception message in white bold font on a red background should show underneath the XamComboEditor but that does not work - instead I see a red border and exception message in default font to the side of the control. That same ControlTemplate works just fine with standard WPF ComboBox - I checked. 

From reading this forum I've seen a couple of suggestions on re-templating XamComboEditor but I have not been able to redefine it to match my ControlTemplate (below). One of these discussions is located here: http://es.infragistics.com/community/forums/t/48422.aspx

If re-templating the XamComboEditor is really the correct solution for this problem, I would appreciate a sample utilizing my Validation.ErrorTemplate snippet below. Thanks!

XAML definition of the control:

<ig:XamComboEditor
ItemsSource="{Binding MyList}"
SelectedItem="{Binding SelectedItem, Mode=TwoWay, ValidatesOnDataErrors=True}"
Validation.ErrorTemplate="{StaticResource ComboBoxErrorTemplate}"
EmptyText="Choose item..."
DisplayMemberPath="Name"
IsEditable="True"
AutoComplete="True"
AllowDrop="False"/>

and my Validation control template:

<ControlTemplate x:Key="ComboBoxErrorTemplate">
<StackPanel Orientation="Vertical">
<AdornedElementPlaceholder x:Name="ErrorAdorner">
    <Border BorderBrush="Blue" BorderThickness="1" />
</AdornedElementPlaceholder>
<TextBlock Text="{Binding AdornedElement.(Validation.Errors).[0].ErrorContent, ElementName=ErrorAdorner}" Background="Blue" Foreground="White" FontWeight="Bold" VerticalAlignment="Center"/>
</StackPanel>
</ControlTemplate>