Is there a way to lock research paths?

[DanielM]

I agree that locking research paths is a must.

Another possiblity I have seen in other games:

The bars can be used as weights, i.e. each bar can take any value between 0 and 100 independently from the others. The amount of points allocated to each path is then determined by (weight for this path)/(total sum of weights)*(number of points available).

Though that would probably be more difficult to implement than simple locking.