Boolean CommandParameter in XAML

This might be a bit of a hack but you can derive from the KeyBinding class:

public class BoolKeyBinding : KeyBinding
{
    public bool Parameter
    {
        get { return (bool)CommandParameter; }
        set { CommandParameter = value; }
    }
}

Usage:

<local:BoolKeyBinding ... Parameter="True"/>

And another not so weird solution:

xmlns:s="clr-namespace:System;assembly=mscorlib"

<Application.Resources>
    <!-- ... -->
    <s:Boolean x:Key="True">True</s:Boolean>
    <s:Boolean x:Key="False">False</s:Boolean>
</Application.Resources>

Usage:

<KeyBinding ... CommandParameter="{StaticResource True}"/>

Or, maybe that:

<Button.CommandParameter>
    <s:Boolean>True</s:Boolean>
</Button.CommandParameter>

Where s is the namespace:

 xmlns:s="clr-namespace:System;assembly=mscorlib"

The easiest is to define the following in the Resources

<System:Boolean x:Key="FalseValue">False</System:Boolean>
<System:Boolean x:Key="TrueValue">True</System:Boolean>

and use it like:

<Button CommandParameter="{StaticResource FalseValue}"/>