In my project I am using the xamgrid with some UnboundColumns.
In reading mode I have no issue. But I cannot ge the edit mode to work.
If I simply needed a IValueConverter I could get thigs to work following the sample provided but, for various reasons, I need to use a IMultiValueConverter instead.
This IMultiValueConverter need to take in the datacontect (UnboundDataContext) or the ColumnKey at a minimum.

FOr the EditorTemplate I started with the sample provided in your website below:
<DataTemplate x:Key="Sample">
<StackPanel Orientation="Vertical">
<Slider x:Name="slider1" SmallChange="1" LargeChange="1" DataContext="{Binding RowData}" Value="{Binding TestProperty, Converter={StaticResource subPropertyColumnConverter}, ConverterParameter={RelativeSource Self}}" />
<TextBlock Text="{Binding Value, ElementName=slider1}" HorizontalAlignment="Center"/>
</StackPanel>
</DataTemplate>

This compiles and "works" except that I would not enough information passed into the converter to do what I need

so I changed it to:

<DataTemplate x:Key="SampleTest">
<StackPanel Orientation="Vertical">
<Slider x:Name="slider1" SmallChange="1" LargeChange="1" DataContext="{Binding RowData}">
<Slider.Value>
<MultiBinding Converter="{StaticResource subPropertyColumnMultiConverter}">
<Binding Path="DataContext" RelativeSource="{RelativeSource Self}"/>
<Binding RelativeSource="{RelativeSource Self}"/>
</MultiBinding>
</Slider.Value>
</Slider>
<TextBlock Text="{Binding Value, ElementName=slider1}" HorizontalAlignment="Center"/>
</StackPanel>
</DataTemplate>

But I constantly crash.

Can you please provide a sample that shows how to edit an unboundcolumn using an IMultiValueParameter?

Thank you.