title: VS suddenly refuses to show usercontrols
body: <p>I have a winforms project and I also have a dll with own made usercontrols.  </p>
  
  <ul>
  <li>What I did was start a new winforms project</li>
  <li>In the toolbox right mouse
  <code>choose items</code></li>
  <li>browse to myControls.dll</li>
  <li>all controls are found and checked, then I click on <code>OK</code></li>
  </ul>
  
  <p>This worked on friday, and I was able to drag some controls on my form.<br>
  But today the controls are gone again.<br>
  So I repeat all the steps from above but it does not helps anymore</p>
  
  <p>What I tried :  </p>
  
  <ul>
  <li>in toolbox right mouse <code>show all</code></li>
  <li>Checked <code>Tools -&gt; Options -&gt; Windows Forms Designer</code> that the property <code>Automatically Populate Toolbox</code> is set to true  </li>
  <li>Rebuild the project  </li>
  <li>Reloaded the project</li>
  <li>Restarted VS</li>
  <li>Checked the target and framework are the same for the project and the dll</li>
  <li>Reset Toolbox</li>
  </ul>
  
  <p>Nothing helps, the controls just refuse to show up.</p>
  
  <p>What can cause a dll with usercontrols to load in the Toolbox one day and not anymore the next day ?<br>
  Nothing has changed in the library and nothing has changed in the winforms project.  I just shut down VS and came back to work again today and found it like this.</p>
  
  <p>Also, the usercontrols are used in several other projects without any troubles</p>
  
  <p>EDIT:<br>
  The controls I was able to drag on the form on friday are all working without problems. So I guess there really is nothing wrong with the dll.</p>
  
  <p>EDIT:<br>
  in other winforms projects the controls do still show up in the toolbox. Just as they did in this project on friday...</p>