<Page xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"> <StackPanel HorizontalAlignment="Center" VerticalAlignment="Center"> <Button Name="btn1" FontSize="12" Margin="12" HorizontalAlignment="Center"> Expand Other Button </Button> <Button Name="btn2" FontSize="12" Margin="12" HorizontalAlignment="Center"> Expand Other Button </Button> </StackPanel> <Page.Triggers> <EventTrigger SourceName="btn1" RoutedEvent="Button.Click"> <BeginStoryboard> <Storyboard> <DoubleAnimation Storyboard.TargetName="btn2" Storyboard.TargetProperty="FontSize" From="12" To="48" Duration="0:0:2" FillBehavior="Stop" /> </Storyboard> </BeginStoryboard> </EventTrigger> <EventTrigger SourceName="btn2" RoutedEvent="Button.Click"> <BeginStoryboard> <Storyboard> <DoubleAnimation Storyboard.TargetName="btn1" Storyboard.TargetProperty="FontSize" From="12" To="48" Duration="0:0:2" FillBehavior="Stop" /> </Storyboard> </BeginStoryboard> </EventTrigger> </Page.Triggers> </Page>