<Window x:Class="WpfApplication1.Window1" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="WPF" Height="300" Width="300"> <Canvas Margin="5"> <Canvas.Resources> <!--scRGB semi-transparent color--> <SolidColorBrush Color="sc# 0.8,0.3,0.9,0.25" x:Key="Brush1" /> </Canvas.Resources> <Rectangle Canvas.Top="5" Canvas.Left="5" Fill="{StaticResource Brush1}" Height="180" Width="80" /> </Canvas> </Window>