LicenseDialog.xaml

<Window xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
        x:Class="Demo.Wpf.LicenseDialog"
        Title="Configure DotNetBrowser license" 
        Height="250" 
        MinWidth="350"
        WindowStartupLocation="CenterScreen" 
        SizeToContent="WidthAndHeight"
        ResizeMode="CanMinimize">
    <Grid MinWidth="350">
        <Grid.RowDefinitions>
            <RowDefinition Height="*" />
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
        </Grid.RowDefinitions>
        <TextBlock x:Name="tbMessage" Margin="50 10 0 0"
                   HorizontalAlignment="Left" MaxWidth="380"
                   FontSize="14"
                   TextWrapping="Wrap" />
        <TextBox x:Name="inputBox" Grid.Row="1" Margin="15 0 15 10" Width="450" />

        <StackPanel Grid.Row="2" Margin="15,10,15,10" Orientation="Horizontal" HorizontalAlignment="Right">
            <Button MinWidth="100" MinHeight="25" 
                    Click="ApplyButton_Click"
                    IsDefault="True" Padding="10, 0, 10, 0"
                    Content="Apply and start the demo" HorizontalContentAlignment="Center"/>
        </StackPanel>
    </Grid>
</Window>