<Window x:Class="WpfApplication1.Window1" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="Simple Animation" Height="165" Width="428"> <StackPanel Margin="20"> <Rectangle Name="SimpleGreenRectangle" Fill="Green" Width="50" Height="30" /> <StackPanel Orientation="Vertical" Margin="0,20,0,0"> <Button Name="startButton">Start</Button> <Button Name="stopButton">Stop</Button> <StackPanel.Triggers> <EventTrigger SourceName="startButton" RoutedEvent="Button.Click"> <BeginStoryboard Name="myStoryboard"> <Storyboard> <DoubleAnimation Storyboard.TargetName="SimpleGreenRectangle" Storyboard.TargetProperty="Width" From="50" To="300" Duration="0:0:2" RepeatBehavior="Forever" /> </Storyboard> </BeginStoryboard> </EventTrigger> <EventTrigger SourceName="stopButton" RoutedEvent="Button.Click"> <StopStoryboard BeginStoryboardName="myStoryboard" /> </EventTrigger> </StackPanel.Triggers> </StackPanel> </StackPanel> </Window>