<Page xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" HorizontalAlignment="Center" VerticalAlignment="Center"> <Ellipse Name="myEllipse" Fill="Red" Height="100" Width="10"> <Ellipse.Triggers> <EventTrigger RoutedEvent="Ellipse.MouseEnter"> <BeginStoryboard Name="changeWidth"> <Storyboard> <DoubleAnimation Storyboard.TargetProperty="(Ellipse.Width)" To="300" Duration="0:0:5" /> </Storyboard> </BeginStoryboard> </EventTrigger> <EventTrigger RoutedEvent="Ellipse.MouseLeftButtonDown"> <PauseStoryboard BeginStoryboardName="changeWidth" /> </EventTrigger> </Ellipse.Triggers> </Ellipse> </Page>