Nested Grid
<Window x:Class="LayoutPanels.SharedSizeGroup" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="SharedSizeGroup" Height="300" Width="380"> <Grid Grid.IsSharedSizeScope="True" Margin="3"> <Grid.RowDefinitions> <RowDefinition></RowDefinition> <RowDefinition Height="Auto"></RowDefinition> <RowDefinition></RowDefinition> </Grid.RowDefinitions> <Grid Grid.Row="0" Margin="3" Background="LightYellow" ShowGridLines="True"> <Grid.ColumnDefinitions> <ColumnDefinition Width="Auto" SharedSizeGroup="TextLabel"></ColumnDefinition> <ColumnDefinition Width="Auto"></ColumnDefinition> <ColumnDefinition></ColumnDefinition> </Grid.ColumnDefinitions> <Grid Grid.Row="2" Margin="3" Background="LightYellow" ShowGridLines="True"> <Grid.ColumnDefinitions> <ColumnDefinition Width="Auto" SharedSizeGroup="TextLabel"></ColumnDefinition> <ColumnDefinition></ColumnDefinition> </Grid.ColumnDefinitions> <Label Margin="5">Short</Label> <TextBox Grid.Column="1" Margin="5">A text box</TextBox> </Grid> </Grid> </Grid> </Window>