A Simple Computation API with Progress Tracking

<Window x:Class="SimpleComputation.WpfDemo.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="clr-namespace:SimpleComputation.WpfDemo"
        Title="SimpleComputation Demo" Height="360" Width="545" ResizeMode="NoResize">
    <Grid>
        <Grid.DataContext>
            <local:MainViewModel />
        </Grid.DataContext>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
            <RowDefinition />
        </Grid.RowDefinitions>

        <StackPanel Margin="6 6 6 0" Orientation="Horizontal">
            <Button Content="Simple Computation" Command="{Binding Commands[RunSimpleComputation], Mode=OneTime}" />
            <Button Content="Exception Throwing Computation" Command="{Binding Commands[RunExceptionComputation], Mode=OneTime}" Margin="5 0 0 0" />
            <Button Content="Mixed Progress Computation" Command="{Binding Commands[RunProgressComputation], Mode=OneTime}" Margin="5 0 0 0" />
        </StackPanel>

        <StackPanel Grid.Row="1" VerticalAlignment="Center" HorizontalAlignment="Stretch" Margin="25 15" >
            <TextBlock Text="{Binding Returned, Mode=OneWay}" HorizontalAlignment="Center"  Margin="0 0 0 10"/>            
            <StackPanel DataContext="{Binding CurrentComputation.Progress, Mode=OneWay}" >
                <TextBlock Text="{Binding StatusText, Mode=OneWay}" />
                <ProgressBar Height="25" 
                                 IsIndeterminate="{Binding IsIndeterminate, Mode=OneWay}"
                                 Minimum="0"
                                 Maximum="{Binding Length, Mode=OneWay}"
                                 Value="{Binding Current, Mode=OneWay}" />
            </StackPanel>
            <Button Content="Cancel Computation" Command="{Binding Commands[Cancel], Mode=OneTime}" HorizontalAlignment="Right" Margin="0 5 0 0" />
        </StackPanel>

        <ListBox Grid.Row="2" ItemsSource="{Binding ComputationProgressLog, Mode=OneWay}" Margin="6 0 6 6">
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <StackPanel Orientation="Horizontal">
                        <TextBlock Text="{Binding StatusText, Mode=OneTime}" Margin="0 0 5 0" />
                        <TextBlock><Run Text="{Binding Current, Mode=OneTime}" /><Run Text="/" /><Run Text="{Binding Length, Mode=OneTime}" />
                        <Run Text=" indeterminate: " /><Run Text="{Binding IsIndeterminate, Mode=OneTime}" /></TextBlock>
                    </StackPanel>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>
    </Grid>
</Window>