The following example shows how to apply animation in the thickness of a Border control by using ThicknessAnimation class:
[XAML]
<Window x:Class="Window1" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="Window1" Height="211" Width="425"> <Grid Height="171" Width="400"> <Border CornerRadius="80" Background="#ffffff" BorderBrush="#2a3b57" BorderThickness="5" Height="77" Margin="141,39,123,0" Name="Border1" VerticalAlignment="Top" > <Border.Triggers> <EventTrigger RoutedEvent="Border.Loaded"> <BeginStoryboard> <Storyboard> <ThicknessAnimation Storyboard.TargetProperty="BorderThickness" Duration="0:0:1.5" FillBehavior="HoldEnd" From="1,1,1,1" To="15,15,15,15" /> </Storyboard> </BeginStoryboard> </EventTrigger> </Border.Triggers> <TextBlock Background="#ffffff" HorizontalAlignment="Center" VerticalAlignment="Center" Height="34" Width="69" TextWrapping="Wrap"> Welcome to AuthorCode </TextBlock> </Border> </Grid> </Window>