<Window x:Class="WPF控件_3_内容原则.MainWindow"
        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"
        Title="MainWindow" Height="450" Width="800">
    <StackPanel>
        <Button Margin="3">
            <Grid>
                <Polygon Points="100,25 100,0 200,25 125,50" Fill="LightBlue" />
                <Polygon Points="100,25 75,0 0,25 75,50" Fill="White" />
            </Grid>
        </Button>
    </StackPanel>

</Window>