Select
Each graph element (vertices, edges) can be selected by a click close to it.
It becomes selected when the mouse button is released and only if we don't
move the mouse during pressing the button. We use left mouse button to select
vertices and right button to select edges. If we don't use any control key,
all previously selected elements become unselected, if we are holding SHIFT
key, their state don't change.
When we try to select already selected element, it becomes unselected.
So we can unselect all elements by a left click close to any selected vertex
or right click close to any selected edge.
Add
We can add new element(s) to the graph, if we hold down CTRL key, while we
make a click. New element is added when the mouse button is released and only
if we don't move the mouse during pressing the button. With a left click we can
add new vertex, which become connected to each previously selected vertex,
with a right click we connect the nearest vertex to each of them. If we are
holding the SHIFT key too, new edges will be directed.
Delete
Graph element can be deleted by a click, while we are holding the ALT key.
We can delete vertices with left click and edges with right click.
If we are holding the SHIFT key too, all selected vertices/edges will be
deleted instead of the nearest one.
Move
Moving graph elements is very easy. First we must determine the graph
elements we want to move. With left and right button we choose among
vertices and edges, with the SHIFT key we determine, that we will move
all selected elements instead of the nearest one. While we hold the
mouse button, choosen elements will move in the same directeon as mouse
pointer.
Properties
Properties of graph elements can be edited by a double click. With left
and right click we choose bettween vertices and edges, with the SHIFT key
we determine that we will edit the properties of all selected elements
instead of the properties of the nearest element.