How to stretch in width a WPF user control to its window?

Question

I have a Window with my user control and I would like to make usercontrol width equals window width. How to do that?

The user control is a horizontal menu and contains a grid with three columns:

<ColumnDefinition Name="LeftSideMenu" Width="433"/> <ColumnDefinition Name="Middle" Width="*"/> <ColumnDefinition Name="RightSideMenu" Width="90"/> 

That is the reason I want the window width, to stretch the user control to 100% width, with the second column relative.

EDIT:

I am using a grid, there is the code for Window:

<Window x:Class="TCI.Indexer.UI.Operacao"     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"     xmlns:tci="clr-namespace:TCI.Indexer.UI.Controles"     Title=" " MinHeight="550" MinWidth="675" Loaded="Load" ResizeMode="NoResize" WindowStyle="None" WindowStartupLocation="CenterScreen" WindowState="Maximized" Focusable="True"     x:Name="windowOperacao">     <Canvas x:Name="canv">         <Grid>             <tci:Status x:Name="ucStatus"/> <!-- the control which I want to stretch in width -->         </Grid>     </Canvas> </Window> 

Answer 1

You need to make sure your usercontrol hasn't set it's width in the usercontrol's xaml file. Just delete the Width="..." from it and you're good to go!

EDIT: This is the code I tested it with:

SOUserAnswerTest.xaml:

<UserControl x:Class="WpfApplication1.SOAnswerTest"     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"     Height="300">     <Grid>         <Grid.ColumnDefinitions>             <ColumnDefinition Name="LeftSideMenu" Width="100"/>             <ColumnDefinition Name="Middle" Width="*"/>             <ColumnDefinition Name="RightSideMenu" Width="90"/>         </Grid.ColumnDefinitions>         <TextBlock Grid.Column="0">a</TextBlock>         <TextBlock Grid.Column="1">b</TextBlock>         <TextBlock Grid.Column="2">c</TextBlock>     </Grid> </UserControl> 

Window1.xaml:

<Window x:Class="WpfApplication1.Window1"     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"     xmlns:local="clr-namespace:WpfApplication1"     Title="Window1" Height="300" Width="415">     <Grid>          <local:SOAnswerTest Grid.Column="0" Grid.Row="5" Grid.ColumnSpan="2"/>     </Grid> </Window>