showconfig offers "previous" and "next" [parameter group] links to list configuration for other trees. Unhappily, the link is built using HTML-relative form which implies 'virtroot' is not changed and new modes links still point to the original tree.
The "previous" and "next" links should be computed according to the same algorithm as that used for the "speed switch" button in the page header area. The basic code already exist in Template.pm. Since this code manipulates configuration parameters, a new method should be created in Config.pm to be shared by Template.pm and Config.pm.