Playing around with XAML animations tonight. I should be placed against the wall for this, but I couldn't resist. Might start a new craze...

Open up XAMLPad and past this rubbish into it:

<Page xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:sys="clr-namespace:System;assembly=mscorlib" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" >
  <Page.Resources>
    <Style TargetType="Border" x:Key="PageBackground">
      <Setter Property="Background" Value="#eeeeff" />
    </Style>
  </Page.Resources>
  <Grid Background="#aaaabb" Width="450" Height="120">
    <Border Style="{StaticResource PageBackground}" Margin="1.5,1.5,1.5,1.5" Name="mainBorder">
      <Border.Triggers>
        <EventTrigger RoutedEvent="Border.Loaded">
          <BeginStoryboard>
            <Storyboard>
              <DoubleAnimation
                Storyboard.TargetName="mainBorder"
                Storyboard.TargetProperty="Width"
                From="400"
                To="450"
                Duration="0:0:0.25"
                AutoReverse="True"
                RepeatBehavior="Forever" />
            </Storyboard>
          </BeginStoryboard>
          <BeginStoryboard>
            <Storyboard>
              <DoubleAnimation
                Storyboard.TargetName="mainBorder"
                Storyboard.TargetProperty="Height"
                From="100"
                To="120"
                Duration="0:0:0.25"
                AutoReverse="True"
                RepeatBehavior="Forever" />
            </Storyboard>
          </BeginStoryboard>
        </EventTrigger>
      </Border.Triggers>
      <StackPanel Margin="5,5,5,5">
        <StackPanel Orientation="Horizontal">
          <Label Width="100">User ID:</Label>
          <TextBox Width="200" Margin="5,5,5,5" Name="userIDTextBox">
            <!--<TextBox.BitmapEffect>
              <DropShadowBitmapEffect/>
            </TextBox.BitmapEffect> -->
            <TextBox.Triggers>
              <EventTrigger RoutedEvent="TextBox.Loaded">
                <BeginStoryboard>
                  <Storyboard>
                    <DoubleAnimation
                      Storyboard.TargetName="userIDTextBox"
                      Storyboard.TargetProperty="Opacity"
                      From="1.0"
                      To="0.0"
                      Duration="0:0:0.25"
                      AutoReverse="True"
                      RepeatBehavior="Forever" />
                  </Storyboard>
                </BeginStoryboard>
              </EventTrigger>
            </TextBox.Triggers>
          </TextBox>
        </StackPanel>
        <StackPanel Orientation="Horizontal">
          <Label Width="100">Password:</Label>
          <TextBox Width="200" Margin="5,5,5,5">
            <TextBox.BitmapEffect>
              <BitmapEffectGroup>
                <DropShadowBitmapEffect />
                <BlurBitmapEffect Radius="1" />
              </BitmapEffectGroup>
            </TextBox.BitmapEffect>
          </TextBox>
        </StackPanel>
        <StackPanel Orientation="Horizontal" HorizontalAlignment="Right">
          <Button Width="100" Margin="5" Name="loginButton" >
           Login
            <Button.Triggers>
              <EventTrigger RoutedEvent="Button.Loaded">
                <BeginStoryboard>
                  <Storyboard>
                    <DoubleAnimation
                      Storyboard.TargetName="loginButton"
                      Storyboard.TargetProperty="Opacity"
                      From="0.75"
                      To="0.5"
                      Duration="0:0:0.5"
                      AutoReverse="True"
                      RepeatBehavior="Forever" />
                  </Storyboard>
                </BeginStoryboard>
              </EventTrigger>
            </Button.Triggers>
          </Button>
          <Button Width="100" Margin="5" >Exit</Button>
        </StackPanel>
      </StackPanel>
    </Border>
  </Grid>
</Page>