Change other's property - wpf

Question

Right now, I'm learning WPF. Can we change another WPF object's property when an WPF object's property is changed?
Below is simplified scenario.
I have a Window with a TextBox named m_Text and a ToggleButton named m_Button. I want to change the m_Text.Background property if m_Button is pressed, that is m_Button.IsChecked = true. I think it's possible using a Trigger but I don't know how to do it.
P.S. If possible, I want to do it only in XAML.

Answer 1

WPF makes this really easy - you can databind the TextBox's Background property directly to the IsChecked property on the ToggleButton. Of course, you will need to convert the IsChecked (boolean) to be a Brush, but WPF allows you to specify a Converter object right in the binding...
In code, you create an object that implements IValueConverter, and implement the Convert method, like
public class BoolToBrushConverter : IValueConverter
{
#region IValueConverter Members
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
bool isChecked = (bool)value;
string[] colours = parameter.ToString().Split(':');
if (isChecked)
return new BrushConverter().ConvertFromString(colours[0]);
return new BrushConverter().ConvertFromString(colours[1]);
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}
#endregion
}
then in xaml you need to add the namespace containing this class, declare an instance of the converter as a resource within the window, then use it in the Binding... it should look something like this:
<Window x:Class="WpfApplication1.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:WpfApplication1"
Title="Window1" Height="300" Width="300">
<Window.Resources>
<local:BoolToBrushConverter x:Key="boolToBrushConverter" />
</Window.Resources>
<StackPanel Height="250">
<ToggleButton Name="toggleButton" Height="32" Content="Green" />
<TextBox
Background="{Binding ElementName=toggleButton, Path=IsChecked, Converter={StaticResource boolToBrushConverter}, ConverterParameter=Green:White}" />
</StackPanel>
</Window>
UPDATE: As per Ivan's excellent suggestion - have updated to show how you can pass parameters through to the Converter from the XAML...