extendablity

@@ -237,7 +237,8 @@ grid.prototype = {
         });
         var h_t = column.display || "";
         c.html(h_t);
-        if (column.type) c.html("<input type='" + column.type + "' class='wqt_all' />");
+        var input_class=column._class||"wqt_all";
+        if (column.type) c.html("<input type='" + column.type + "' class='"+input_class+"' />");
         return column.hidden ? "" : c;
     },
     ajax: function(param) {

@@ -44,9 +44,10 @@ var promotionEdit={
                 {
                     display: '',
                     type: 'checkbox',
-                    render: function (item) {                        
+                    _class:"all",
+                    render: function (item) {
                         var htmlContent = "";
-                        var _class="wqt_checkbox";
+                        var _class="promotion_checkbox";
                         if(g.batchIds.length === 0 ){
                             //htmlContent = "<input type='checkbox' class='wqt_checkbox' data-index='"+item.__index+"'>";
                             htmlContent = g.buildCheckboxHtml(_class,item.__index);