<esri:FeatureLayer.MapTip>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<ItemsControl ItemsSource="{Binding Keys}" Grid.Column="0" />
<ItemsControl ItemsSource="{Binding Values}" Grid.Column="1" />
</Grid>
</esri:FeatureLayer.MapTip>