Manage string attribute on group

issue6611
review35581002

src/sao.less

@@ -190,6 +190,10 @@ button {
     .panel-heading {
         padding: 1px 1px;
     }
+    & fieldset.form-group_ > legend {
+        font-size: @font-size-base;
+        margin-bottom: 5px;
+    }
 }
 
 .form-binary, .editabletree-binary {

src/view/form.js

@@ -789,9 +789,12 @@ function eval_pyson(value){
         class_: 'form-group_',
         init: function(attributes) {
             Sao.View.Form.Group._super.init.call(this, attributes);
-            this.el = jQuery('<div/>', {
+            this.el = jQuery('<fieldset/>', {
                 'class': this.class_
             });
+            if (attributes.string) {
+                this.el.append(jQuery('<legend/>').text(attributes.string));
+            }
         },
         add: function(widget) {
             this.el.append(widget.el);