GTK2 How to work with 32bpp image pixels?

[ALLIGATOR]

Lazarus, Linux, LCL, GTK2

How can I make it normal?
(Under Windows, a 10x10 pixel square, as expected)

Code: Pascal  [Select][+][-]

1. procedure TForm1.FormCreate(Sender: TObject);
2. var
3.   pData: PUint32;
4.   x, y: integer;
5. begin
6.   Image1.Width:=20;
7.   Image1.Height:=20;
8.  
9.   Image1.Picture.Bitmap.PixelFormat:=pf32bit;
10.   Image1.Picture.Bitmap.Width:=20;
11.   Image1.Picture.Bitmap.Height:=20;
12.  
13.   Caption := TypInfo.GetEnumName(TypeInfo(TPixelFormat), Ord(Image1.Picture.Bitmap.PixelFormat));
14.   Caption := Caption + ', ' + Image1.Picture.Bitmap.RawImage.Description.BitsPerPixel.ToString;
15.  
16.   Image1.Picture.Bitmap.BeginUpdate();
17.   for y:=0 to 9 do
18.   begin
19.     pData:=PUInt32(Image1.Picture.Bitmap.RawImage.GetLineStart(y));
20.     for x:=0 to 9 do
21.       PUInt32(pData)[x]:=$FFFFFFFF;
22.   end;
23.   Image1.Picture.Bitmap.EndUpdate();
24. end;