Altering the keyboard functionality

    <Window.Resources>

         <!--UI commands.-->

        <RoutedUICommand x:Key="Commands.ZoomOut" />

        <RoutedUICommand x:Key="Commands.ZoomIn" />

    </Window.Resources>

    <Window.InputBindings>       

        <!--Bind keys to commands.-->       

        <KeyBinding   Key="Minus"  Command="{StaticResource Commands.ZoomOut}"   />

        <KeyBinding   Key="Plus"  Command="{StaticResource Commands.ZoomIn}"  />

        <KeyBinding   Key="Space" Command="{StaticResource Commands.ZoomIn}"  />     

    </Window.InputBindings>

    <Window.CommandBindings>       

        <!--Bind commands to event handlers.-->       

        <CommandBinding  Command="{StaticResource Commands.ZoomOut}"  Executed="ZoomOut_Executed" />

        <CommandBinding  Command="{StaticResource Commands.ZoomIn}"            Executed="ZoomIn_Executed" />

    </Window.CommandBindings>