message: Fixed autocomplete dropshadow (win)
diff: <Popup Name="popup" x:FieldModifier="private"
  MaxHeight="500" StaysOpen="True" AllowsTransparency="True">
  <Grid>
  + <Grid.Effect>
  + <DropShadowEffect BlurRadius="8" ShadowDepth="2" Opacity="0.3" Direction="270" />
  + </Grid.Effect>
  <TextBlock Name="emptyLabel" x:FieldModifier="private"
  HorizontalAlignment="Center" VerticalAlignment="Center"
  Margin="4"
  Text="Hello. Yes, this is list."/>
  - <ListBox x:Name="listBox" HorizontalAlignment="Stretch" Height="200" Margin="0,0,0,0"
  + <ListBox x:Name="listBox" HorizontalAlignment="Stretch" Height="200" Margin="10,0,10,10"
  + BorderThickness="0"
  VerticalAlignment="Top" Width="400"
  VirtualizingStackPanel.VirtualizationMode="Recycling"
  ItemTemplateSelector="{StaticResource autocompleteTemplateSelector}"
  ItemsSource="{Binding Items}" PreviewMouseDown="listBox_PreviewMouseDown"
  SelectionChanged="listBox_SelectionChanged">
  - <ListBox.Effect>
  - <DropShadowEffect BlurRadius="8" ShadowDepth="2" Opacity="0.3" Direction="270" />
  - </ListBox.Effect>
  <ListBox.ItemContainerStyle>
  <Style TargetType="ListBoxItem">
  <Setter Property="HorizontalContentAlignment" Value="Stretch"></Setter>
  