
The following problem arises frequently. A graph is constructed by drawing it 
in a GraphWin
and the combinatorial structure of the graph is supposed to reflect the
drawing, i.e., for every node v the cyclic order of A(v) is supposed
to agree with the counter-clockwise order of the edges out of v in the
drawing. 

The LEDA function sort_edges solves this task. This demo illustrates it.
As you construct a graph, the adjacency lists are shown in the window in which
the demo was started. 




