title: How can I detect a held down mouse button over a PictureBox?
body: <p>I need to fire an event when the mouse is above a PictureBox with the mouse button already clicked and held down.</p>
  
  <p>Problems: </p>
  
  <p>The MouseDown and MouseEnter event handlers do not work together very well.</p>
  
  <p>For instance once a mouse button is clicked and held down, C# will fire the MouseDown event handler, but when the cursor moves over the PictureBox the MouseEnter event does not fire, until the mouse button is realeased.</p>