The description of these behaviors is termed the mechanism. When scientists are not provided with such a mechanism, then a description of a process, it's explanation, or it's understanding, is questioned. Astrology does not work with mechanisms. It works with relationships, patterns, tendencies, and interpretations. It does not always give a yes or no answer.
I hate the Drawing Canvas and I understand that it's not backward compatible, so I never use it. To turn it off in Word 2002 and above, go to Tools 4 Options, General tab. Untick Automatically create drawing canvas....
The line tool is used to draw straight lines on the canvas. It is pretty intuitive, you simply choose the line tool from the toolbox, click once on the canvas to specify the beginning point of your line and then drag the mouse to define the line extending from the starting point.