Starting an animation with a trigger
<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'> <Ellipse Name="myEllipse" Fill="Red" Height="100" Width="10"> <Ellipse.Triggers> <EventTrigger RoutedEvent="Ellipse.MouseEnter"> <BeginStoryboard> <Storyboard> <DoubleAnimation Storyboard.TargetProperty="(Ellipse.Width)" To="300" Duration="0:0:5" /> </Storyboard> </BeginStoryboard> </EventTrigger> </Ellipse.Triggers> </Ellipse> </UserControl>