title: How to diplay/call an UserControl from another UserControl at click both situated in one MainWindow (C#/Xaml)
body: <p>I'm pretty stuck right now, i'm gonna explain my problem and what i want. 
  In my <strong>solution</strong> i have a <strong>mainWindow</strong>, in that <strong>MainWindow</strong> i call the <strong>first userControl</strong> Who is situated in an <strong>userControlLibrary</strong>. I'ts a menu with button. I want when i click on the first button of the first userControl, i want put the <strong>visibility</strong> of the <strong>second usercontrol</strong> to <strong>visible</strong> (too situated in the <strong>userControlLibrary</strong>). But i try many things but no one works. </p>
  
  <p>The first userControl is <strong>UC_MenuSlider</strong> and <strong>UC_Start_Study</strong> is the second who have to be visibile after click on the button on the first one. At launch <strong>UC_Start_Study is hidden</strong>.</p>
  
  <p>This is a part of the code of my <strong>Mainwindow</strong>: </p>
  
  <pre><code>&lt;Grid Name="MainGrid"&gt;
  
      &lt;Grid.ColumnDefinitions&gt;
          &lt;ColumnDefinition Width="*"/&gt;
      &lt;/Grid.ColumnDefinitions&gt;
      &lt;UserControlLibrary:UC_StartStudy x:Name="UC_Start_Study"  Grid.Column="1" Height="Auto" Width="Auto" Margin="70 0 0 0" Visibility="Hidden"/&gt;
  
     &lt;Grid&gt;
          &lt;Grid.ColumnDefinitions&gt;
              &lt;ColumnDefinition Width="0.1*" MaxWidth="240" MinWidth="240" /&gt;
              &lt;ColumnDefinition Width="*"/&gt;
          &lt;/Grid.ColumnDefinitions&gt;
          &lt;UserControlLibrary:UC_MenuSlider x:Name="UC_MenuSlider"  Grid.Column="0"/&gt;
     &lt;/Grid&gt;
  
  &lt;/Grid&gt;
  </code></pre>
  
  <p>A part of the code of my first <strong>UserControl (UC_MenuSlider)</strong>: </p>
  
  <pre><code>&lt;Grid Name="Grid_Menu" HorizontalAlignment="Stretch"&gt;
  
      &lt;Grid.RowDefinitions&gt;
       &lt;RowDefinition Height="*"/&gt;
      &lt;/Grid.RowDefinitions&gt;
  
  
      &lt;Button x:Name="Start_Study"   Grid.Row="0" Grid.Column="0"  Margin="0" Content="Start Study" FontSize="16" Click="Start_Study_Click"&gt;
      &lt;/Button&gt;
  &lt;/Grid&gt;
  </code></pre>
  
  <p>At first a basic event,just an event click in my first userControl. with code behind like that:</p>
  
  <pre><code>public void Start_Study_Click(object sender, RoutedEventArgs e)
  {
      var startStudy = new UserControlLibrary.UC_StartStudy();
      startStudy.Visibility = Visibility.Visible;
  }
  </code></pre>
  
  <p>Don't works. Then i use 'RoutedEvent' But I don't really understand who it works.</p>
  
  <p>I hope my question was enough clear, thanks in advance for your anwsers</p>