(sorry, this has nothing to do with Futurama!)
Probably the biggest new feature of FinalBuilder 4 is the ASync action group. It opens massive possibilities in your build process - in short, it allows you to run multiple actions simultaneously with sync points.
Unfortunately, we had to impose a limitation with this, namely that you couldn't run other actions lists or include other FinalBuilder projects under the ASync action group. The reason behind this was that Actions are not re-entrant, this means that if Action A was running (say compiling a VS.Net solution) then if that same action was also called by another thread then it would cause major problems. So, this needed to be prevented and hence the limitation as allowing run action list and including FB projects is the only way that you could get the situation where FB would be able to run the same instance of an action multiple times. Sorry if I lost you, the good news is almost here :)
The limitation for a lot of people made ASync action groups not very useful, as the majority of their actions are split up into separate action groups... so it'd be like one step forwards, two steps back. We were planning to revisit this for a 4.1 release... but because of so many people asking us about it, and because it's pretty much the only thing people were critical of in FB4, it was decided to fix it!
Well, as you could probably guess - the limitation is now gone! Now ASync Action Groups can contain both Run Action list actions and Include FinalBuilder project actions!
A small new limitation needed to be added... (that's Professor Hubert Farnsworth bad news :)... but the limitation is a lot less limiting. The limitation is that a single action can not be run at the same time. So, for example if you have a Compile action in an action list and your ASync action group contains two Run Action List actions both calling the same action list with the Compile action, then if the compile action is actually running and the second thread wants to run the compile action, then it must wait until the first one is finished. In other words, running the same FB actions at the same time is serialised.