title: How to get display resolution (screen size)?
body: <p>How to get display resolution in XNA/Monogame ? 
  I tried these on my monitor (1600x900):</p>
  
  <p>The below give me 800,600</p>
  
  <pre><code>//1.
  GraphicsDevice.DisplayMode.Width
  GraphicsDevice.DisplayMode.Height
  
  //2.
  GraphicsDeviceManager graphics = new GraphicsDeviceManager(this);
  graphics.GraphicsDevice.DisplayMode.Width
  graphics.GraphicsDevice.DisplayMode.Height
  
  //3.
  GraphicsAdapter.DefaultAdapter.CurrentDisplayMode.Width
  GraphicsAdapter.DefaultAdapter.CurrentDisplayMode.Height
  
  //4.
  foreach (DisplayMode dm in GraphicsAdapter.DefaultAdapter.SupportedDisplayModes)
  {
      Console.WriteLine(dm.Width);
      Console.WriteLine(dm.Height);
  }
  </code></pre>