Window SubClassing另类运用（之二）[9]

  if assigned(oldbrowseproc) then

    result := oldbrowseproc(awnd, umsg, wp, lp);

end;

在newbrowseproc中必须处理几条消息。第一个就是用户在combobox中选择一项的时候，在treeview中必须同步跳转到同样的文件夹：

    case umsg of

wm_command:

      if hiword(wp)=cbn_selchange then begin

         hcombo := getdlgitem(awnd, idc_combo);

         index := sendmessage(hcombo, cb_getcursel, 0, 0);

         if index=cb_err then exit;

         csidl := sendmessage(hcombo, cb_getitemdata, index, 0);

         if csidl<>555 then begin // csidl

            shgetspecialfolderlocation(awnd, csidl, pidl);

            sendmessage(awnd, bffm_setselection, 0, longint(pidl));

            cotaskmemfree(pidl);

         end

         else begin // normal folder

           setlength(str, max_path);

           sendmessage(hcombo, cb_getlbtext, index, longint(pchar(str)));

           str := pchar(str);