Blending semi-transparent bitmaps containing text with Graphics32

I'm trying to implement a layered painting system inside one of our internal components and I have problems blending bitmaps containing text.

Following code fragment shows the problem:

uses
  GR32;

procedure DrawBitmaps;
var
  bmp1: TBitmap32;
  bmp2: TBitmap32;
begin
  bmp1 := TBitmap32.Create;
  bmp1.Width := 100;
  bmp1.Height := 100;
  bmp1.FillRect(0, 0, 100, 100, clWhite32);
  bmp1.FillRect(0, 0, 80, 80, clTrGreen32);

  bmp1.Font.Size := -16;
  bmp1.Font.Color := clBlack;
  bmp1.TextOut(2, 10, 'Green');

  bmp1.SaveToFile('c:\0\bmp1.bmp');

  bmp2 := TBitmap32.Create;
  bmp2.Width := 80;
  bmp2.Height := 80;
  bmp2.FillRect(0, 0, 80, 80, clTrRed32);

  bmp2.Font.Size := -16;
  bmp2.Font.Color := clBlack;
  bmp2.TextOut(2, 50, 'Red');

  bmp2.SaveToFile('c:\0\bmp2.bmp');

  bmp2.DrawMode := dmBlend;
  bmp2.DrawTo(bmp1, 20, 20);

  bmp1.SaveToFile('c:\0\bmpcombined.bmp');

  bmp1.Free;
  bmp2.Free;
end;

Resulting images:

bmp1: bmp2: bmpcombined:

As you can see, text is painted in black on bmp and bmp2, but appears white on bmpcombined.

I'm guessing the problem lies in TextOut which maps to Windows.ExtTextOut (via GR32_Backends_VCL.pas, TGDIBackend.Textout). That method doesn't handle transparency and paints text with alpha 00 (color is $000000 instead of $FF000000).

As a quick fix, setting bmp2.Font.Color to $FF000000 doesn't help.

bmp2.Font.Color := TColor(clBlack32);

I am using fresh sources from GitHub

How should I paint a non-transparent text on a semi-transparent background so that I could blend this into a larger picture?