title: ImageList: 32-bit Images lose quality
body: <p>I'm using <code>ImageList</code> for <code>TreeView</code> and <code>ListView</code>. I've first set the image quality to 32 bit and then added images which are semi-transparent. The quality looks OK, but after a couple of minutes coding, compiling and executing the application, the quality looks bad.</p>
  
  <p>See screenshot: 
    <img src="https://i.stack.imgur.com/odNk1.jpg" alt="enter image description here"></p>
  
  <p>Used properties</p>
  
  <pre><code>ColorDepth: Depth32Bit
  ImageSize: 16; 16
  TransparentColor: Transparent
  </code></pre>
  
  <p>There are black pixels behind pixels which were semi-transparent but not fully transparent.</p>
  
  <p>Re-adding all images restores the original quality, but after a couple of minutes, it looks like on the right side of the screenshot.</p>