The Straight Line tool is available from the Freehand and Brush fly out menu. Simply select the tool and click and drag the required direction in order to draw your straight line. The tool provides a simple method to create a straight line for example with an arrowhead applied.
For versions prior to version 6, please use one of the methods mentioned below.
You can use the CTRL key when drawing lines to constrain them to 45° angles, allowing easy drawing of straight horizontal or vertical lines.
Try the following example:
Switch to the Shape Editor tool
On the InfoBar select 'Make Line' (L)
Click on the canvas to create the start point of your line
Hold CTRL then click and hold the left mouse button where you want the line to end
As you drag the mouse you can see the line is constrained to 45° angles.
N.B. The Angle Constraint is configurable from:
Utilities > Options > General
From the Editing options choose the Angle Constraint dropdown menu.