Add background color to selected rows

issue8210
review273121002

src/sao.less

@@ -64,6 +64,8 @@
     white-space: nowrap;
 }
 
+.table-row-variant(selected, @state-info-bg);
+
 .tab-form, .tab-board {
     nav.toolbar.affix {
         top: @navbar-height + 1px;

src/view/tree.js

@@ -1168,6 +1168,11 @@
                 return;
             }
             this.selection.prop('checked', value);
+            if (value) {
+                this.el.addClass('selected');
+            } else {
+                this.el.removeClass('selected');
+            }
             if (!value) {
                 this.tree.selection.prop('checked', false);
             }