How about I just make a feature suggestion, which could add quite a bit of expressibility......
Could we have a two controls on a line's style. One for the "frequency" of the dash, ideally something measured in points or some known absolute length. btw the "default" should be such that the minimum length line in the overall graph as at least 3 cycles of dashes within it's length.
The second would be "pattern" and would be created by a sequence of numbers. A simple 50% dash would be "1,1" a 33% dash would be "1,3." If you wanted to get fancy, then something like "1,1,1,3" would appear as a double dash and then short blank spot. "1,1" would be good default. also "1,0" could be a solid line and "0,1" could be an invisible line. There is nothing preventing a line line "39,27" or something equally goofy. remember, these are for the relative pattern within a single dash period, and are not absolute lengths.
Thanks so much for great software!!!!