Sorry for the ress, but I solve this in Persona with HTML and CSS, just declarating the Sidebar widget-area in categories.tpl and CSS to fix the categories width.
I'm newbie with front-end, but this "fix" is functional atm.
Live threads in sidebar
Is it possible somehow to have a sidebar widget that displays the live threads for the category the user is in when viewing a post in that category? So for example you are viewing this thread in the technical support category, in the sidebar now you'd see the latest threads (not individual posts) in technical support. If a new thread is posted as you're reading this, that widget would update with that thread at the top...