You can also do something similar with less hand crafting, if you use the catlist plugin and you use it something like that for creating separate sections:
Both lines go AT THE SAME TIME in one page called "sidebar"
<catlist wiki -smallHead -titleHead:"Wiki">
<catlist playground -smallHead -titleHead:"Playground">
This will make the namespaces to be section titles just like on the dokuwiki page (in the case of playground you need to add pages into it (type in search "playground:newpage" -> then create page) and then edit and save the actual playground page without content to convert it to pageless namespace to get the same section title effect for the playground namespace too)
Also tick the checkmark in the admin configuration for:
"Disable page cache where catlist is used"
Combine it with the folded plugin for expandable bits (with page creating buttons from catlist plugin):
<catlist wiki -addPageButtonEach -smallHead -titleHead:"Wiki">
++++ Playground |
<catlist playground -addPageButtonEach -noHead>