The basic syntax and usage of a GridSplitter
<UserControl x:Class='SilverlightApplication3.MainPage' 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' xmlns:ext="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls" d:DesignWidth='640' d:DesignHeight='480'> <Grid x:Name="LayoutRoot" Background="White"> <Grid.RowDefinitions> <RowDefinition></RowDefinition> <RowDefinition></RowDefinition> <RowDefinition></RowDefinition> </Grid.RowDefinitions> <Grid.ColumnDefinitions> <ColumnDefinition></ColumnDefinition> <ColumnDefinition></ColumnDefinition> <ColumnDefinition></ColumnDefinition> </Grid.ColumnDefinitions> <Canvas Background="Silver" Margin="10" /> <Canvas Background="Gray" Margin="10" Grid.Column="1" /> <Canvas Background="Silver" Margin="10" Grid.Column="2" /> <ext:GridSplitter Width="2" /> <Canvas Background="Gray" Margin="10" Grid.Row="1" /> <Canvas Background="Silver" Margin="10" Grid.Column="1" Grid.Row="1" /> <Canvas Background="Gray" Margin="10" Grid.Column="2" Grid.Row="1" /> <ext:GridSplitter Background="Black" Width="2" Grid.Column="1" Grid.RowSpan="2" /> <Canvas Background="Silver" Margin="10" Grid.Row="2" /> <Canvas Background="Gray" Margin="10" Grid.Column="1" Grid.Row="2" /> <Canvas Background="Silver" Margin="10" Grid.Column="2" Grid.Row="2" /> </Grid> </UserControl>