Auto sizing Silverlight controls

I am using Silverlight 4 for a project. I want to know if there is a way I can get the main canvas to stretch to the height and width of the browser window it is hosted in?

I want the controls within to resize in proportion to the main control that hosts all the rest of the controls in the host browser window. This is a Prism application which has a Shell.xaml and a ContentControl within the shell. In this prism case I want the content control to span to 100% of the screen height and width.. and when a Page.xaml loads within it I want the Page's usercontrol to fill up the entire content control of the xaml. Similarly, within the Page.xaml if I have a grid I want the grid to grow to a size no more than a fixed number of pixels

The Grid within the Page.xaml's user control seems to be sizing properly. I am having trouble getting the root user control of the Page.xaml to stretch to the entire width of the browser window. Is there a way this can be done using xaml properties only? I dont want to specify the height and width to 800 and 1200 like I have done below.

This is my code

<UserControl x:Class="MyNamespace.MyClass"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="400" 
xmlns:sdk="http://schemas.microsoft.com/winfx/2006/xaml/presentation/sdk"
Background="#FF2D8543" 
Height="800" Width="1200"
 >

<Grid x:Name="LayoutRoot" Background="#FFEB0A0A" 
VerticalAlignment="Center" HorizontalAlignment="Center"
Height="Auto" Width="Auto"
 >
</Grid>

Thanks for your time.

Yes, use Grid instead of Canvas as top level element. Grid takes all the available space by default.

Learn more about Silverlight layout system here and here.

Update:

Just remove Width and Height attributes from the UserControl:

Height="800" Width="1200"

By setting those explicitly you are giving the control fixed size. If you don't specify Width and Height the control will take all the available space.