WPF

private const Brush greenBrush = new SolidColorBrush(Colors.Green);
private const Brush redBrush = new SolidColorBrush(Colors.Red);
private Brush currentBrush;
private int oldValue;
private int currentValue;

public Brush Background
{
  get { return currentBrush; }
}

public int CurrentValue
{
  get
  {
    return currentValue;
  }
  set
  {
    if (currentValue == value) return;
    oldValue = currentValue;
    currentValue = value;
    if (oldValue < currentValue)
      currentBrush = redBrush;
    else
      currentBrush = greenBrush;
    OnChanged("CurrentValue");
    OnChanged("CurrentBrush");
    OnChanged("Difference");
  }
}

public int Difference
{
  get { return Math.Abs(currentValue - oldValue); }
}

Clifford Nelson wrote:

acts as a converter that changes model information into view information and
passes commands from the view into the model. The view model exposes public
properties, commands, and abstractions. The view model has been likened to a
conceptual state of the data as opposed to the real state of the data in the
model.

Clifford Nelson wrote:

Color is not an abstraction. You should be able to replace the View with a
totally different implementation and still work.

Clifford Nelson wrote:

If it is decided that a different color should be used, that should not affect
the ViewModel, any more than changing the position of the textbox should affect
the ViewModel.

<Window x:Class="DynamicGrid.MainWindow"
				xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
				xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
				xmlns:local="clr-namespace:DynamicGrid"
				Title="MainWindow"
				Height="350"
				Width="525">
	<Window.DataContext>
		<local:ViewModel />
	</Window.DataContext>
	<Grid>
		<DataGrid AutoGenerateColumns="True"
							ItemsSource="{Binding Children}"
							HorizontalAlignment="Stretch"
							Name="dataGrid1"
							VerticalAlignment="Stretch" />
	</Grid>
</Window>

class ViewModel
{
    public ViewModel()
    {
        var temp = new BindingList<Class1>();
        temp.Add(new Class1 {TypeA = "AAAA", TypeB = "BBBB"});
        temp.Add(new Class1 { TypeA = "CCCC", TypeB = "CCCC" });
        _children = temp;
    }
    private IEnumerable<object> _children;
    public IEnumerable<object> Children
    {
        get { return _children; }
        set { _children = value; }
    }
}

<ListBox ItemsSource="{Binding Source={MyEmulatorsList, XPath=//Kind}" ItemTemplate="{StaticResource KindItemsTemplate}" />

<DataTemplate x:Key="KindItemsTemplate">
  <TextBlock Text="{Binding XPath=@name}" />
</DataTemplate>

<Emulators>
    <System>
        <Gear>Name1</Gear>
        <Kind name="att1"/>
        <Kind name="att2"/>
        <Kind name="att3"/>
    </System>
</Emulators>

Class MainWindow
    Dim data As XmlDataProvider = New XmlDataProvider()
    Private Sub MainWindow_Initialized(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Initialized
        data.Source = New Uri(Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData) & "\myapplication\Systems.xml")
        data.XPath = "Emulators/System"
        Grid1.DataContext = data
    End Sub
End Class

<Window x:Class="MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:WpfApplication1"         
    Title="MainWindow" Height="350" Width="525" Background="#FF4E4E64">
    <Grid Name="Grid1">
        <Grid.Resources>
            <DataTemplate x:Key="KindTemplate">
                <TextBlock Text="{Binding XPath=@name}" />
            </DataTemplate>
        </Grid.Resources>
        <TextBox Text="{Binding XPath=Gear, UpdateSourceTrigger=PropertyChanged}" Height="23" HorizontalAlignment="Left" Margin="197,230,0,0" Name="TextBox3" VerticalAlignment="Top" Width="220" />
        <ListBox ItemsSource="{Binding Source=data, XPath=//Kind}" ItemTemplate="{StaticResource KindTemplate}" Margin="261,51,12,149" />
        </Grid>
</Window>

System.Windows.Data Error: 44 : BindingExpression with XPath cannot bind to non-XML object.; XPath='//Kind' BindingExpression:Path=; DataItem='String' (HashCode=2037252866); target element is 'ListBox' (Name=''); target property is 'ItemsSource' (type 'IEnumerable') data