При использовании поведения:
вам понадобится разметка, подобная этой:
<Window xmlns:i=
"clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"
xmlns:custom=
"clr-namespace:CustomBehaviorsLibrary;assembly=CustomBehaviorsLibrary >
пример:
<Canvas>
<Rectangle Canvas.Left="10" Canvas.Top="10" Fill="Yellow" Width="40" Height="60">
</Rectangle>
<Ellipse Canvas.Left="10" Canvas.Top="70" Fill="Blue" Width="80" Height="60">
<i:Interaction.Behaviors>
<custom:DragInCanvasBehavior></custom:DragInCanvasBehavior>
</i:Interaction.Behaviors>
</Ellipse>
<Ellipse Canvas.Left="80" Canvas.Top="70" Fill="OrangeRed" Width="40" Height="70">
<i:Interaction.Behaviors>
<custom:DragInCanvasBehavior></custom:DragInCanvasBehavior>
</i:Interaction.Behaviors>
</Ellipse>