Get Password Box

// Set password characters for the Edit Field
procedure SetPasswordChar(AHandle: HWND; Value: Char);
var
  S: String;
  len: Integer;
begin
  len := Sendmessage(AHandle, WM_GETTEXTLENGTH, 0, 0);
  SetLength(S, len);
  SendMessage(AHandle, WM_GETTEXT, len+1, lparam(@S[1]));
  SendMessage(AHandle, EM_SETPASSWORDCHAR, Ord(Value), 0);
  SendMessage(AHandle, WM_SETTEXT, 0, Integer(PChar(S)));
end;

// Cancel the password characters and reveal the text
procedure CancelPasswordChar(AHandle: HWND);
var
  S: string;
  len: Integer;
begin
  len := SendMessage(AHandle, WM_GETTEXTLENGTH, 0, 0);
  SetLength(S, len);
  SendMessage(AHandle, WM_GETTEXT, len + 1, lParam(@S[1]));
  SendMessage(AHandle, EM_SETPASSWORDCHAR, 0, 0);
  SendMessage(AHandle, WM_SETTEXT, 0, Integer(PChar(S)));
end;

// Beispiel:
procedure TForm1.Button1Click(Sender: TObject);
var
  wnd: HWND;
begin
  wnd := FindWindowEx(GetForeGroundWindow, 0, 'TEdit', nil);
  if wnd <> 0 then
    SetPasswordChar(wnd,'*');
end;