title: C# exclude complete form / usercontrol by using compiler constants
body: <p>I'd like to exclude / include a complete form in my project. But when I add the needed <code>#if CONST</code> and <code>#endif</code> the compiler complains about resources that may get wrong names.</p>
  
  <blockquote>
    <p>warning MSB3042: A namespace or class definition was found within a conditional compilation directive in the file "Form1.cs". This may lead to an incorrect choice for the manifest resource name for resource "Form1.resx".</p>
  </blockquote>
  
  <p>What does this mean?</p>
  
  <p>And how do I fix it?</p>