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    <p>It was a bit of a design mistake in Winforms to make the BufferedGraphicsXxx classes public. They are an implementation detail of double-buffering support in Winforms and they are not terribly resilient to using them wrong.</p> <p>You are definitely using the BufferedGraphics you get back from Allocate() wrong. You create buffers at a high rate, inside the game loop. But you forget to dispose the buffer you used at the end of the loop. This will consume device contexts (HDC's) at a high rate. That doesn't go on forever, if your program doesn't otherwise get the garbage collector running then Windows pulls the plug and will not let you create a new device context. The internal CreateCompatibleDC() call will fail and returns NULL. The BufferedGraphicsContext class otherwise misses the code to check for this error and plows on with the NULL handle. And starts painting to the desktop window instead of the form.</p> <p>A fix will be to move the Allocate() call outside of the loop so you do it just once. But now you'll have a new problem when the user changes the window size, the buffer is no longer the correct size.</p> <p>The better mousetrap is to just not use the BufferedGraphics class but leave it up to Winforms to get it right. There are several ways to get a gameloop in Winforms, but the simplest one is to just use the OnPaint() method to render the scene and immediately ask for another paint so it keeps getting called over and over again. Similar to this:</p> <pre><code>public partial class Form1 : Form { public Form1() { InitializeComponent(); this.DoubleBuffered = true; this.ResizeRedraw = true; } protected override void OnPaint(PaintEventArgs e) { RenderScene(e.Graphics); this.Invalidate(); } } </code></pre> <p>Where RenderScene() should draw the game objects, using the passed Graphics instance. Note that you no longer need to use Clear(), that was already done.</p>
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    1. POGraphics are rendered outside the form with GDI+
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    1. COIsn't calling `Invalidate()` at the end of `OnPaint` going to use a lot of power when nothing moves, though?
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    2. COCertainly, it burns 100% core, drawing the frames as fast as possible. Just like his original game loop does. The form otherwise stays completely responsive to input, painting is a low priority task. If that's a problem then the simplest solution is a Timer whose Tick event handler calls Invalidate(). A 15 msec Interval gets 64 fps, 30 msec gets 32 fps, assuming it can keep up.
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