title: Why does RegisterHotKey return false? user32.dll
body: <p>when i run <code>RegisterHotKey</code>, it returns false. what are possible reasons?</p>
  
  <pre><code>internal void RegisterHotKey2(ModifierKeys modifier, Keys key)
  {
      _cID += 1;
      if (!RegisterHotKey(_window.Handle, _cID, (uint)modifier, (uint)key))
      {
          Console.WriteLine("oh no: " + modifier.ToString() + " + " + key.ToString());
          throw new InvalidOperationException("couldn't register noooooo");
      }
  }
  </code></pre>
  
  <p><strong>OLD VERSION (don't judge please)</strong></p>
  
  <pre><code>internal void RegisterHotKey2(ModifierKeys modifier, Keys key)
  {
      _cID += 1;
      if (!RegisterHotKey(_window.Handle, _cID, (uint)modifier, (uint)key))
          Console.WriteLine("oh no: " + modifier.ToString() + " + " + key.ToString());
      throw new InvalidOperationException("couldn't register noooooo");
  }
  </code></pre>