Add a class to show scroll bars even in OS X which hides them

resources/frontend_client/app/css/core/scroll.css

+
+.scroll-show::-webkit-scrollbar {
+    width: 15px;
+    height: 18px;
+}
+.scroll-show::-webkit-scrollbar-thumb {
+    height: 6px;
+    border: 4px solid transparent;
+    border-radius: 7px;
+    background-clip: padding-box;
+    background-color: #c2c2c2;
+}
+
+.scroll-show::-webkit-scrollbar-button {
+    width: 0;
+    height: 0;
+    display: none;
+}
+.scroll-show::-webkit-scrollbar-corner {
+    background-color: transparent;
+}
+
+.scroll-show:hover::-webkit-scrollbar-thumb {
+    background-color: #7d7d7d;
+}
+.scroll-show::-webkit-scrollbar-thumb:horizontal:hover,
+.scroll-show::-webkit-scrollbar-thumb:vertical:hover {
+    background-color: #7d7d7d;
+}
+.scroll-show::-webkit-scrollbar-thumb:horizontal:active,
+.scroll-show::-webkit-scrollbar-thumb:vertical:active {
+    background-color: #7d7d7d;
+}

resources/frontend_client/app/query_builder/AccordianList.react.js

@@ -103,7 +103,7 @@ export default class AccordianList extends Component {
                             </div>
                         : null }
                         { openSection === sectionIndex ?
-                            <ul style={{maxHeight: 400}} className="p1 border-bottom scroll-y">
+                            <ul style={{maxHeight: 400}} className="p1 border-bottom scroll-y scroll-show">
                               {section.items.map((item, itemIndex) => {
                                   return (
                                       <li key={itemIndex} className={cx("List-item flex", { 'List-item--selected': this.itemIsSelected(item) })}>