Dead keys cannot be handled in TForm.OnUTF8KeyPress

[AlexTP]

Original very detailed report:
https://github.com/Alexey-T/CudaText/issues/5002
In the topic, user even has shown the keyboard layout (Portuguese, ABNTII).

My Lazarus test program, with the source, is attached there too.
It shows that app cannot see accented letters in TForm.OnUTF8KeyPress.
Can you help, Zeljko?

Code: Pascal  [Select][+][-]

1. unit Unit1;
2.  
3. {$mode objfpc}{$H+}
4.  
5. interface
6.  
7. uses
8.   Classes, SysUtils, Forms, Controls, Graphics, Dialogs, StdCtrls, LCLType;
9.  
10. type
11.  
12.   { TForm1 }
13.  
14.   TForm1 = class(TForm)
15.     ListBox1: TListBox;
16.     procedure FormKeyDown(Sender: TObject; var Key: Word; Shift: TShiftState);
17.     procedure FormUTF8KeyPress(Sender: TObject; var UTF8Key: TUTF8Char);
18.   private
19.  
20.   public
21.  
22.   end;
23.  
24. var
25.   Form1: TForm1;
26.  
27. implementation
28.  
29. {$R *.lfm}
30.  
31. { TForm1 }
32.  
33. function _hexstr(const c: TUTF8Char): string;
34. var
35.   i: integer;
36. begin
37.   result:= '';
38.   for i:= 1 to length(c) do
39.     result+= HexStr(Ord(c[i]), 2)+' ';
40. end;
41.  
42. procedure TForm1.FormUTF8KeyPress(Sender: TObject; var UTF8Key: TUTF8Char);
43. begin
44.   Listbox1.Items.Add('keypress: '+UTF8Key+', hex: '+_hexstr(UTF8Key));
45.   Listbox1.ItemIndex:= Listbox1.Items.Count-1;
46. end;
47.  
48. procedure TForm1.FormKeyDown(Sender: TObject; var Key: Word; Shift: TShiftState);
49. begin
50.   Listbox1.Items.Add('keydown: '+IntTostr(key));
51.   Listbox1.ItemIndex:= Listbox1.Items.Count-1;
52. end;
53.  
54. end.
55.