Added thumbstyle that demonstrates the use of Visuals of controls.

ResizingControls/Window1.xaml

@@ -2,11 +2,10 @@
 <Window
 	x:Class="ResizingControls.Window1"
 	xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
-	xmlns:interactive="clr-namespace:Shared.InteractiveBehaviors;assembly=Shared"
-    xmlns:attached="clr-namespace:Shared.AttachedBehaviors;assembly=Shared"
+	xmlns:attached="clr-namespace:Shared.AttachedBehaviors;assembly=Shared"
 	xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"
-
-    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+	xmlns:interactive="clr-namespace:Shared.InteractiveBehaviors;assembly=Shared"
+	xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
 	Width="700"
 	Height="500"
 	Background="Beige"
@@ -18,22 +17,22 @@
 			<Setter Property="MaxWidth" Value="600"/>
 			<Setter Property="MinHeight" Value="30"/>
 			<Setter Property="MinWidth" Value="100"/>
-            <Setter Property="Width" Value="100" />
-            <Setter Property="Height" Value="50" />
+			<Setter Property="Width" Value="100"/>
+			<Setter Property="Height" Value="50"/>
 			<Setter Property="HorizontalAlignment" Value="Center"/>
 			<Setter Property="VerticalAlignment" Value="Center"/>
 			<Setter Property="Background" Value="AntiqueWhite"/>
-            <Setter Property="ContentTemplate">
-                <Setter.Value>
-                    <DataTemplate>
-                        <Viewbox Stretch="Fill">
-                            <TextBlock Text="{TemplateBinding Content}"/>
-                        </Viewbox>
-                    </DataTemplate>
-                </Setter.Value>
-            </Setter>
+			<Setter Property="ContentTemplate">
+				<Setter.Value>
+					<DataTemplate>
+						<Viewbox Stretch="Fill">
+							<TextBlock Text="{TemplateBinding Content}"/>
+						</Viewbox>
+					</DataTemplate>
+				</Setter.Value>
+			</Setter>
 		</Style>
-		<Style x:Key="resizeThumbStyle" TargetType="{x:Type Thumb}">
+		<Style x:Key="resizeThumbCustomStyle" TargetType="{x:Type Thumb}">
 			<Setter Property="Width" Value="12"/>
 			<Setter Property="Height" Value="12"/>
 			<Setter Property="Cursor" Value="SizeNWSE"/>
@@ -55,6 +54,37 @@
 				</Setter.Value>
 			</Setter>
 		</Style>
+		<Style x:Key="resizeThumbVisualStyle" TargetType="{x:Type Thumb}">
+			<Setter Property="Width" Value="12"/>
+			<Setter Property="Height" Value="12"/>
+			<Setter Property="Cursor" Value="SizeNWSE"/>
+			<Setter Property="Template">
+				<Setter.Value>
+					<ControlTemplate>
+						<Image Width="12" Height="12">
+							<Image.Source>
+								<DrawingImage>
+									<DrawingImage.Drawing>
+										<GeometryDrawing Geometry="M9,0 L11,0 11,11 0,11 0,9 3,9 3,6 6,6 6,3 9,3z">
+											<GeometryDrawing.Brush>
+												<VisualBrush>
+													<VisualBrush.Visual>
+                                                        <ComboBox />
+                                                    </VisualBrush.Visual>
+												</VisualBrush>
+											</GeometryDrawing.Brush>
+										</GeometryDrawing>
+									</DrawingImage.Drawing>
+								</DrawingImage>
+							</Image.Source>
+                            <Image.RenderTransform>
+                                <TranslateTransform X="-8" Y="-8"/>
+                            </Image.RenderTransform>
+						</Image>
+					</ControlTemplate>
+				</Setter.Value>
+			</Setter>
+		</Style>
 	</Window.Resources>
 	<Grid>
 		<Grid.RowDefinitions>
@@ -64,13 +94,13 @@
 		<GroupBox Grid.Row="0" Header="Attached Behaviors">
 			<Label
 				attached:ResizeAttachedBehavior.IsResizeable="true"
-				attached:ResizeAttachedBehavior.ThumbStyle="{StaticResource resizeThumbStyle}"
+				attached:ResizeAttachedBehavior.ThumbStyle="{StaticResource resizeThumbCustomStyle}"
 				Content="ResizeMe"/>
 		</GroupBox>
 		<GroupBox Grid.Row="1" Header="Interactive Behaviors">
-			<Label Content="ResizeMe" >
+			<Label Content="ResizeMe">
 				<i:Interaction.Behaviors>
-					<interactive:ResizeInteractiveBehavior ThumbStyle="{StaticResource resizeThumbStyle}"/>
+					<interactive:ResizeInteractiveBehavior ThumbStyle="{StaticResource resizeThumbVisualStyle}"/>
 				</i:Interaction.Behaviors>
 			</Label>
 		</GroupBox>