<Window x:Class="AnimationSpeed" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="Animation Speed Example" Height="240" Width="410"> <StackPanel Margin="5"> <Rectangle Name="rect3" Fill="Blue" Margin="2" Width="20" Height="20" HorizontalAlignment="Left" /> <Button Margin="2,20,0,0" HorizontalAlignment="Left" Content="Start Animations" Width="100"> <Button.Triggers> <EventTrigger RoutedEvent="Button.Click"> <EventTrigger.Actions> <BeginStoryboard> <Storyboard> <DoubleAnimation Storyboard.TargetName="rect3" Storyboard.TargetProperty="Width" From="20" To="400" Duration="0:0:10" SpeedRatio="0.5" /> </Storyboard> </BeginStoryboard> </EventTrigger.Actions> </EventTrigger> </Button.Triggers> </Button> </StackPanel> </Window>