Me auto-respondo, Lo solucioné de esta manera:
Código Delphi
[-]
function GetText(XHand : THandle):string;
var textlength:integer;
text:PChar;
begin
textlength:=SendMessage(XHand,WM_GETTEXTLENGTH,0,0);
if textlength=0 then Result:='Empty' else
begin
getmem(text,textlength+1);
SendMessage(XHand,WM_GETTEXT,textlength+1,Integer(text));
Result:=text;
freemem(text);
end;
end;