In case anyone ever sees this: Here's what I did to solve this problem: As for the "double" line, don't do it. Make a straight line, then copy it and put another below it. As for making the line straight: First, make the height of the non-straight line as narrow as possible by grabbing the bars and pulling them as close as they can get before it all breaks apart (this step may not be necessary). Second, go to the "Borders" tab of your line and choose the color, style, and width of your still non-straight line. Third, go to to the "Appearance" tab of your line. In the "Size" section, you'll see a 'w' and an 'h' value, in pixels. Change the 'h' value to 1. Finally, you might want to change the location of the line(s). Grabbing them with your mouse ain't gonna work. Instead, go the the "Appearance" tab of your line. In the Location section you'll find x and y values. Mess around with the y value to move the line up or down (lower value = down, higher value = up).