We started the 0.99.xx track in December last year.
Because we want to start moving towards 1.0. An "1.0" of an application is usually the first version of an application that does something useful. It seems that Wings has passed that stage a long time ago.
So in the 0.99.xx track, we will attempt to fix as many bugs and major shortcomings as possible, before we bump the version number to 1.0, probably before the end of the year.