To add
a line to a graph:
-
Click
the line icon

in the Graph toolbar, or select
Insert
Line from the main menu.
-
Position
your cursor at a starting position in the graph.
-
Click
and drag the line in the graph.
If you
press the CTRL key and then click and drag, the line is created from
the center and moves outward.
If you
press SHIFT and then click and drag, then the line's orientation stays
in multiple of 15 degrees. You can create a perfect horizontal or
vertical line this way. You can also rotate the line in 15 degree
increments to create a diagonal line.
If you
press CTRL+SHIFT and then click and drag, the line is created from
the center, moves outward, and can be rotated in 15 degree increments.