// Determine, if a Edit Field has password characters
// Herausfinden, ob das Edit Feld Passwort Charakter hat
function HasPasswordChar(AHandle: HWND): Boolean;
 var
  dwStyle: DWORD;
 begin
  dwStyle := GetWindowLong(AHandle, GWL_STYLE);
  Result := (dwStyle and ES_PASSWORD) = ES_PASSWORD;
 end;
 // Set password characters for the Edit Field
// Passwort Charakter fur ein Edit Feld setzen
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
// Password Charakter aufheben und den Text anzeigen
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;
 // Example:
procedure TForm1.Button1Click(Sender: TObject);
 var
  wnd: HWND;
 begin
  wnd := FindWindowEx(GetForeGroundWindow, 0, 'TEdit', nil);
  if wnd <> 0 then
  SetPasswordChar(wnd,'*');
 end;