title: "current vertex declaration does not include all the elements required"
body: <p>"The current vertex declaration does not include all the elements required by the current vertex shader. TextureCoordinate0 is missing."</p>
  
  <p>I get this error when I try to use a spriteFont to draw my FPS on the screen, on the line where I call spriteBatch.End()</p>
  
  <p>My effect doesn't even use texture coordinates. 
  But I have found the root of the problem, just not how to fix it.
  I have a separate thread that builds the geometry (an LOD algorithm) and somehow this seems to be why I have the problem.
  If I make it non-threaded and just update my mesh per frame I don't get an error.
  And also if I keep it multithreaded but don't try to draw text on the screen it works fine.
  I just can't do both.</p>
  
  <p>To make it even more strange, it actually compiles and runs for a little bit. But always crashes.
  I put a Thread.Sleep in the method that builds the mesh so that it happens less often and I saw that the more I make this thread sleep, and the less it gets called, the longer it will run on average before crashing.
  If it sleeps for 1000ms it runs for maybe a minute. If it sleeps for 10ms it doesn't even show one frame before crashing. This makes me believe that it has to do with a certain line of code being executed on the mesh building thread at the same time you are drawing text on the screen.</p>
  
  <p>It seems like maybe I have to lock something when drawing the text, but I have no clue.
  Any ideas?</p>