The latest Revindex Storefront uses a Telerik RadTreeView control to render the categories. To expand all the categories, you can create a custom display template and add a OnClientLoad event with some javascript.
<%@ Control Language="C#" AutoEventWireup="true" CodeBehind="Display.ascx.cs" Inherits="Revindex.Dnn.RevindexStorefront.Portals._default.Display.Category.Standard3.Display" %>
<%@ Register Assembly="DotNetNuke.Web.Deprecated" Namespace="DotNetNuke.Web.UI.WebControls" TagPrefix="dnn2" %>
<div class="rvdsfCategoryContainer">
<dnn2:DnnTreeView ID="CategoryDnnTreeView" runat="server" ShowLineImages="false" CssClass="rvdsfCategoryTreeView" Skin="" OnClientLoad="CategoryDnnTreeView_Loaded">
<NodeTemplate>
<a href='<%# DataBinder.Eval(Container, "NavigateUrl") %>'>
<%# DataBinder.Eval(Container, "Text") %></a>
</NodeTemplate>
</dnn2:DnnTreeView>
</div>
<script type="text/javascript">
function CategoryDnnTreeView_Loaded(treeView, args)
{
var nodes = treeView.get_allNodes();
for (var i = 0; i < nodes.length; i++)
{
if (nodes[i].get_nodes() != null)
nodes[i].expand();
}
}
</script>