[furbyhater]

Took me less than one minute for drawing the line: - click on the fountain pen (stroke tool) - make a stroke on the canvas (click once for the origin, once for the end) - under Tool Options, click on "Stroke Path" and choose the desired thickness, then click on "Stroke"

Voilà, done (without using Google).

[kiiski]

Or alternatively click on the start point, hold shift and click on the end point.