Alternative Routes

I like the way to assemble or put a route together collecting waypoints by clicking on the map, then push the add button. After the list is complete it will be computed by hitting the magnifying glass I learned.

What I miss is an option to manipulate the computed route by hand. For just a specific leg to became manually adjusted to use a substitue (maybe to use a street, or a bridge, or even climbing a tree) set by hand.