@Ange Tuteur
how can i make each of these prefixes has deference color
i using this JS code

Code:

var prefixes = ["prefix 1","prefix 2"];
        var _pm = false;
        var chk = false;
        function toMenu(a) {
          var htmlpre = '<select style="margin-right:5px" id="prefix" size="1"><option value=""> Prefixes </option>';
          for (i in a)
          htmlpre += '<option value="' + a[i] + '">' + a[i] + '</option>';
          htmlpre += '</select>';
          return htmlpre;
        }
        function checkpre(ar, input) {
          for (i in ar) {
              var p = new RegExp("\" + ar[i], "g");
              var title = input.substr(0, input.indexOf(']'));
              if (p.test(title)) return ar[i];
          }
          return "";
        }
        $(function () {
          if (_pm) chk = /\privmsg/.test(location.href);
          if (/\/post/.test(location.href) || chk) {
              $(toMenu(prefixes)).insertBefore("input[name=subject][type=text]");
              var mw = $("#prefix").width() + 5;
              $("input[name=subject]").css("width", $("input[name=subject]").width() - mw);
              var t = $("[name=subject]").val();
              var cur = checkpre(prefixes, t);
              if (cur != "") {
                $("[value=" + cur + "]").attr("selected", "selected");
                $("input[name=subject]").val(t.replace('[' + cur + ']', '').trim());
              }
              $("input[name=post]").click(function () {
                var sub = $("input[name=subject]").val().trim();
                if (sub != "" && $("#prefix").val() != "")
                    $("input[name=subject]").val("[" + $("#prefix").val() + "] " + sub);
              });
          }
        });

Would it not be easier just to use topic icons, like the solved one on the support forum?  You can create just text images in different colors.

i need it text because searching in google be easy when some one writs the title

i cant explain well because my English is very weak sorry