title: Setting transparent images background in IrfanView
body: <p>I have some PNG images which consist of a black shape and a transparent background.
  Unfortunately, IrfanView shows transparent background as black color, so I see just black on black. I've found in Irfan settings that I can change the window's background color, but it changes only around the image, the transparent color is still black.</p>
  
  <p>Is there any way to change the color displayed as transparent, or, optimally, use white-grey squares like Photoshop?</p>