Add
It creates a new node by clicking on the grid points with the mouse.
Del
It deletes one or more nodes by selecting with the mouse the window with nodes inside.
Move
It moves one or more nodes by selecting with the mouse the window with nodes inside and dragging them on the screen.
Copy
It copies one or more nodes by selecting with the mouse the window with nodes inside: a dialogue box appears for setting the distances on X and Y axis and the number of the copies.
Info
It activates a pointer with a question mark: moving it on the screen and selecting a node, it appears a box with all the information about the selected node.
