TPad and Transparency when using TImage

Hello,
i was looking, if I can find help on TPad and Transparency.

The setting:
I have a star (a christmas star for example) as a png file with a transparent background.
Now I want to draw this Image on Top over a background Image, in such a way that one sees only the star and not the backround of the embedding pad. Unfortunately I havent found a solution yet.
In the code I do the following (as in the tutorials described):

 // Step into BIGCANVAS
   BIGCANVAS->cd();
// Create Pad:
  TPad *p1 = new TPad("i1", "i1", xc-wx/2, yc-wy/2 ,  xc+wx/2, yc+wy/2);
// Open Right Picture:
  TImage *i1 = TImage::Open(Form("xxxx-%d.png",NumberOfPicture));
   i1->SetConstRatio(kFALSE);
 // Draw Pad, then Picture into Pad.
   p1->SetFillStyle(0); // 0 : hollow // strangely this will NOT make the pad transparent !
   p1->SetFillColor(0);
   p1->Draw();
   p1->cd();
   i1->Draw();
   // Step back into BIGCANVAS
   BIGCANVAS->cd();
   BIGCANVAS->Update();

The pad is still white solid filled.
Is there an easy solution?

Best Regards,
Frank

In tutorials/hist there is a transpad.C tutorial, may be, it can help?

I’m also attaching the simplest macro generated by ROOT from a canvas with nested pads and objects.
transp.C (1.04 KB)