title: How to make a groupbox's background transparent?
body: <p>How to set Groupbox to transparent? I found this
  <a href="https://stackoverflow.com/questions/13305797/transparent-background-color-in-tgroupbox-delphi">Transparent</a>,
  But in my case, I put TImage and put a background image, then the Groupbox, I don't know how can I make  the groupbox transparent, and show the image as a background.  </p>
  
  <p>I tried searching this on google, but can't find the answer, and as much as possible, i want to use VCL Application.</p>