TicTacToe/tictactoe/MainWindow.xaml

<Window x:Class="TicTacToe.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:TicTacToe"
        xmlns:c="clr-namespace:TicTacToe"
        mc:Ignorable="d"
        Title="MainWindow" Height="200" Width="200" ResizeMode="NoResize">
    <Window.Resources>
        <c:TicTacToeViewModel x:Key="viewModel" />
    </Window.Resources>
    <Grid DataContext="{StaticResource viewModel}">
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*" />
            <ColumnDefinition Width="*" />
            <ColumnDefinition Width="*" />
        </Grid.ColumnDefinitions>
        <Grid.RowDefinitions>
            <RowDefinition Height="*" />
            <RowDefinition Height="*" />
            <RowDefinition Height="*" />
        </Grid.RowDefinitions>
        <Border BorderBrush="Black" BorderThickness="2" Grid.Row="0" Grid.Column="0">
            <Button Content="{ Binding Field1 }" Style="{ StaticResource Field }" Command="{ Binding FieldClickCommand }" CommandParameter="1" />
        </Border>
        <Border BorderBrush="Black" BorderThickness="2" Grid.Row="1" Grid.Column="0">
            <Button Content="{ Binding Field2 }" Style="{ StaticResource Field }" Command="{ Binding FieldClickCommand }" CommandParameter="2" />
        </Border>
        <Border BorderBrush="Black" BorderThickness="2" Grid.Row="2" Grid.Column="0">
            <Button Content="{ Binding Field3 }" Style="{ StaticResource Field }" Command="{ Binding FieldClickCommand }" CommandParameter="3" />
        </Border>
        <Border BorderBrush="Black" BorderThickness="2" Grid.Row="0" Grid.Column="1">
            <Button Content="{ Binding Field4 }" Style="{ StaticResource Field }" Command="{ Binding FieldClickCommand }" CommandParameter="4" />
        </Border>
        <Border BorderBrush="Black" BorderThickness="2" Grid.Row="1" Grid.Column="1">
            <Button Content="{ Binding Field5 }" Style="{ StaticResource Field }" Command="{ Binding FieldClickCommand }" CommandParameter="5" />
        </Border>
        <Border BorderBrush="Black" BorderThickness="2" Grid.Row="2" Grid.Column="1">
            <Button Content="{ Binding Field6 }" Style="{ StaticResource Field }" Command="{ Binding FieldClickCommand }" CommandParameter="6" />
        </Border>
        <Border BorderBrush="Black" BorderThickness="2" Grid.Row="0" Grid.Column="2">
            <Button Content="{ Binding Field7 }" Style="{ StaticResource Field }" Command="{ Binding FieldClickCommand }" CommandParameter="7" />
        </Border>
        <Border BorderBrush="Black" BorderThickness="2" Grid.Row="1" Grid.Column="2">
            <Button Content="{ Binding Field8 }" Style="{ StaticResource Field }" Command="{ Binding FieldClickCommand }" CommandParameter="8" />
        </Border>
        <Border BorderBrush="Black" BorderThickness="2" Grid.Row="2" Grid.Column="2">
            <Button Content="{ Binding Field9 }" Style="{ StaticResource Field }" Command="{ Binding FieldClickCommand }" CommandParameter="9" />
        </Border>
    </Grid>
</Window>