title: How to make form transparent while keeping the component visible?
body: <p><img src="https://i.imgur.com/ewz7q.jpg" alt=""></p>
  
  <p>I need to make the program which have one form that contains PNG image with transparent area. Form must be invisible, while image must stay visible and transparent area must stay transparent. The problem is image transparency. In this case, main form is transparent, invisible, while all components/controls stays visible. But, transparent area of PNG image doesn't keep transparency. How to keep transparency?</p>
  
  <pre><code>   procedure MakeTransparent;
     var
     AControl: TControl;
     A, Margin, X, Y, CtlX, CtlY: Integer;
     begin
       Margin    := (Width - ClientWidth) div 2;
       FullRgn   := CreateRectRgn(0, 0, Width, Height);
       X         := Margin;
       Y         := Height - ClientHeight - Margin;
     ClientRgn := CreateRectRgn(X, Y, X + ClientWidth, Y + ClientHeight);
     CombineRgn(FullRgn, FullRgn, ClientRgn, RGN_DIFF);
     for A := 0 to ControlCount - 1 do
     begin
      AControl := Controls[A];
      if (AControl is TWinControl) or (AControl is TGraphicControl) then with        AControl do
     begin
      if Visible then
      begin
        CtlX   := X + Left;
        CtlY   := Y + Top;
        CtlRgn := CreateRectRgn(CtlX, CtlY, CtlX + Width, CtlY + Height);
        CombineRgn(FullRgn, FullRgn, CtlRgn, RGN_OR);
      end;
    end;
    end;
    SetWindowRgn(Handle, FullRgn, True);
    end;
  
  
  
    procedure UndoTransparency;
    begin
     FullRgn := CreateRectRgn(0, 0, Width, Height);
     CombineRgn(FullRgn, FullRgn, FullRgn, RGN_COPY);
     SetWindowRgn(Handle, FullRgn, True);
    end;
  </code></pre>