UseFloatingWatermark is not working on ComboBox

[amghw]

<ComboBox Controls:TextBoxHelper.Watermark="Country" Controls:TextBoxHelper.UseFloatingWatermark="True" DisplayMemberPath="country" 
IsEditable="True" ItemsSource="{Binding Countries}" />

Thanks for the wonderful toolkit!

[punker76]

fixed with #2236

[amghw]

Thanks!