Using resources and templates
When building graphical user interfaces, you will often want to use a resource such as a brush to paint the background of controls. These resources can be defined in a single place and shared throughout the app.
Sharing resources
In the Solution Explorer window, double-click on the App.xaml file. Add the following statement to it:
<Application.Resources>
<LinearGradientBrush x:Key="rainbow">
<GradientStop Color="Red" Offset="0" />
<GradientStop Color="Orange" Offset="0.1" />
<GradientStop Color="Yellow" Offset="0.3" />
<GradientStop Color="Green" Offset="0.5" />
<GradientStop Color="Blue" Offset="0.7" />
<GradientStop Color="Indigo" Offset="0.9" />
<GradientStop Color="Violet" Offset="1" />
...