HelloMessageButton_MainWindow.xaml

<Window x:Class="DependencyProperties.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"
        xmlns:local="clr-namespace:DependencyProperties"
        mc:Ignorable="d"
        Title="MainWindow" Height="350" Width="525">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="*"/>
            <RowDefinition Height="25"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>
        
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*"/>
            <ColumnDefinition Width="100"/>
            <ColumnDefinition Width="*"/>
        </Grid.ColumnDefinitions>
        
        <local:HelloMessageButton Grid.Row="1" Grid.Column="1"
                                  Message="You pressed the button!"
                                  >Press The Button</local:HelloMessageButton>
    </Grid>
</Window>