Animation without acceleration or deceleration
<UserControl x:Class='SilverlightApplication3.MainPage' xmlns='http://schemas.microsoft.com/winfx/2006/xaml/presentation' xmlns:x='http://schemas.microsoft.com/winfx/2006/xaml' xmlns:d='http://schemas.microsoft.com/expression/blend/2008' xmlns:mc='http://schemas.openxmlformats.org/markup-compatibility/2006' mc:Ignorable='d' d:DesignWidth='640' d:DesignHeight='480'> <StackPanel Margin="5"> <Rectangle Name="rect1" Fill="Red" 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="rect1" Storyboard.TargetProperty="Width" From="20" To="400" Duration="0:0:10" /> </Storyboard> </BeginStoryboard> </EventTrigger.Actions> </EventTrigger> </Button.Triggers> </Button> </StackPanel> </UserControl>