Node points

How does one lock the node point positions on a map?
Is it possible to add nodes without disturbing existing node point postions?
Why does the map re-draw it'self when a new node is added?

Node points

Sorry, I now realise that my questions have been posed before.
Surely, it's essential that node locking is available.

I have created a very large, complicated map and am becoming increasingly frustrated when it redraws it'self after a minor addition or modification.