Private messages will be redone at some point in the future to be easier to navigate with a mouse. The current design was focused on touch devices and the mouse functionality is lacking.
When I get to revamping PMs I"ll try to improve upon it using the friends list feature once added. Intellesense will be added to the address box as well during the same update.
At this time I have no intentions of doing private threads in the forum since this is what groups are intended for. I will be reworking groups and fixing most of the bugs. I haven't focused on it a lot since groups are widely used at this time.
Sadly, updates have been very slow due to the chaos of the holidays and a lot of family issues getting in the way. I'm slowly getting back to coding again now that things are calming down.
Also got my new laptop fully setup with a fresh development copy of the site and all of the software reloaded. It's VERY fast.
Plus it has a touch which I'm going to be using a ton when creating new layouts to be more Win8 friendly.