Not an answer yet, we're having an issue.  I'm working  up an example now.

Hello Rick,

Thank you for your efforts.

I will be waiting for the sample and I will do my best to investigate it further for you.

I'm going to just have to explain the problem.  So we made custom controls inherited from DataPresenter.Field in order to have standard styled controls.  For example, we made a combobox control.  We want to autosize the combobox with these properties:

            this.Settings.AutoSizeOptions = FieldAutoSizeOptions.All;
            this.Settings.AutoSizeScope = FieldAutoSizeScope.ViewableRecords;
            this.Settings.Width = new FieldLength(50,FieldLengthUnitType.InitialAuto);

The 50 in the FieldLength property has always been kinda quirky, but it works ok.  Well, it works for everything except the situation where we use a multibinding to display more than one value in the drop down. 

So we put the xaml on the usercontrol like this:

<Grid:ComboBoxField Label="My Combo Box"
 Name="MyComboBoxName"
 DisplayMemberPath="MyDisplayPath"
 ItemSourcePath="MySourcePath"
 ItemTemplate="{StaticResource MyTemplate}"/>

and in the resources section we define this style:

<DataTemplate x:Key="MyTemplate">
    <TextBlock>
 <TextBlock.Text>
     <MultiBinding StringFormat="{}{0} - {1}">
  <Binding Path="Part1Path" />
  <Binding Path="Part2Path" />
     </MultiBinding>
 </TextBlock.Text>
    </TextBlock>
</DataTemplate>

Whenever we do this, the comboboxes stretch to about 4 or 5 times what their actual size should be.  How do I fix this so the multibindings work properly?

Hello Rick,

I have been looking into your last post and I can suggest replacing the StringFormat in the MultiBinding of the TextBlock with MultiValueConverter like :

    <Window.Resources>

        <local:MyConverter x:Key="sumConverter"/>

    </Window.Resources>

    <MultiBinding  Converter="{StaticResource sumConverter}" >

              ...

    </MultiBinding>

The MultiValueConverter can look like :

 class MyConverter : IMultiValueConverter

    {

        public object Convert(object[] values, Type targetType, object parameter, System.Globalization.CultureInfo culture)

        {

            string total = null;

            foreach (string val in values)

                total += " " + val;

            return total;

        }

        public object[] ConvertBack(object value, Type[] targetTypes, object parameter, System.Globalization.CultureInfo culture)

        {

            throw new NotImplementedException();

        }

    }

Would you please check whether the value of the total variable which the Converter returns as a result contains unwished empty spaces which make the field extends.

If this does not meet your scenario would you please provide me a small, isolated sample that represents your issue.

I am looking forward to hearing from you.

That was a better format for the drop down, but the column still does not auto size properly.  Is it something to do with the cellpresenterstyle or cellvaluepresenterstyle?