title: How to hide/show the background image of pictureBox?
body: <p>I have a pictureBox with an image inside.
  I want, when i click on a button the image should hide and click again to show the image. </p>
  
  <p>In the pictureBox, using paint event i am drawing some lines.
  So if im doing <code>pictureBox1.Refresh();</code> it will draw the lines. I want that if i click on a button the image will not display on/off.</p>
  
  <p><code>pictureBox1 = null;</code> or <code>pictureBox1.Image.Dispose();</code> doesn't work it's showing me big red x with white background.</p>