<UserControl.Styles>
        <Style
            Selector="Button.KeyboardButton">
            <Setter
                Property="Command"
                Value="{Binding OnKeyClicked}" />
        </Style>
    </UserControl.Styles>

    <Grid
        Classes="DefaultForm"
        ColumnDefinitions="*,*,*"
        RowDefinitions="*,*,*,*">

        <!-- TODO: uncomment -->

        <!-- 123 -->
        <Button
            Grid.Column="0"
            Grid.Row="0"
            Content="1"
            CommandParameter="1"
            Classes="KeyboardButton"/>
        <!-- Style="{StaticResource KeyboardButton}" -->

        <Button
            Grid.Column="1"
            Grid.Row="0"
            Content="2"
            CommandParameter="2"
            Classes="KeyboardButton"/>
        <!-- Style="{StaticResource KeyboardButton}" -->

        <Button
            Grid.Column="2"
            Grid.Row="0"
            Content="3"
            CommandParameter="3"
            Classes="KeyboardButton"/>
        <!-- Style="{StaticResource KeyboardButton}" -->

        <!-- 456 -->
        <Button
            Grid.Column="0"
            Grid.Row="1"
            Content="4"
            CommandParameter="4"
            Classes="KeyboardButton"/>
        <!-- Style="{StaticResource KeyboardButton}" -->

        <Button
            Grid.Column="1"
            Grid.Row="1"
            Content="5"
            CommandParameter="5"
            Classes="KeyboardButton"/>
        <!-- Style="{StaticResource KeyboardButton}" -->

        <Button
            Grid.Column="2"
            Grid.Row="1"
            Content="6"
            CommandParameter="6"
            Classes="KeyboardButton"/>
        <!-- Style="{StaticResource KeyboardButton}" -->

        <!-- 789 -->
        <Button
            Grid.Column="0"
            Grid.Row="2"
            Content="7"
            CommandParameter="7"
            Classes="KeyboardButton"/>
        <!-- Style="{StaticResource KeyboardButton}" -->

        <Button
            Grid.Column="1"
            Grid.Row="2"
            Content="8"
            CommandParameter="8"
            Classes="KeyboardButton"/>
        <!-- Style="{StaticResource KeyboardButton}" -->

        <Button
            Grid.Column="2"
            Grid.Row="2"
            Content="9"
            CommandParameter="9"
            Classes="KeyboardButton"/>
        <!-- Style="{StaticResource KeyboardButton}" -->

        <!-- C0← -->
        <Button
            Grid.Column="0"
            Grid.Row="3"
            Content="C"
            CommandParameter="1"
            Command="{Binding OnClearClicked}" />
        <!-- Style="{StaticResource ClearButton}" -->

        <Button
            Grid.Column="1"
            Grid.Row="3"
            Content="0"
            CommandParameter="0"
            Classes="KeyboardButton"/>
        <!-- Style="{StaticResource KeyboardButton}" -->

        <!-- TODO: replace for symbol-->
        <Button
            Grid.Column="2"
            Grid.Row="3"
            Content="Backspace"
            Command="{Binding OnBackspaceClicked}" />
        <!-- Style="{StaticResource BackspaceButton}" -->
    </Grid>