@bep said:
Try http://drivingdimensions.com/SketchUp/overview/
Bep
That is a really cool plugin which seem to have the feature I was asking about, so thank you very much.
However, I'll agree with @Dave R that it is important to get familiar (or at least somewhat familiar !) with the native tools before installing plugins as they probably require one to learn even more which will only lead to more frustration and confusion.