Binding window's background

I want to bind the background of a window to some string property, such that I'll have a gradient background in different colors when the property changes:

<Window.Background>
    <LinearGradientBrush>
        <LinearGradientBrush.GradientStops>
            <GradientStop Color="White" Offset="0"/>
            <GradientStop Color="{Binding Source={RelativeSource Mode=Self}, 
                                          Path=backgroud_color}" Offset="1"/>
        </LinearGradientBrush.GradientStops>
    </LinearGradientBrush>
</Window.Background>

code behind:

public event PropertyChangedEventHandler PropertyChanged;

private string _backgroud_color;
public string backgroud_color
{
   get { return _backgroud_color; }
   set
   {
      _backgroud_color = value;
      OnPropertyChanged("backgroud_color");
   }
}

public void OnPropertyChanged(string开发者_开发问答 property_name)
{
   if (PropertyChanged != null)
      PropertyChanged(this, new PropertyChangedEventArgs(property_name));
}

but the background does not change at all. What is the problem?

The problem is the RelativeSource in the Binding. It'll refer to the GradientStop which doesn't have a backgroud_color Property. Have you set the DataContext for the Window? In that case, you can just bind to backgroud_color like this

<Window.Background>
    <LinearGradientBrush>
        <LinearGradientBrush.GradientStops>
            <GradientStop Color="White" Offset="0.5"/>
            <GradientStop Color="{Binding Path=backgroud_color}" Offset="1" />
        </LinearGradientBrush.GradientStops>
    </LinearGradientBrush>
</Window.Background>

Code behind

public MainWindow()
{
    InitializeComponent();
    this.DataContext = this;
}

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