First of all I have to say congratulations for the great job done! Your library is not only growing fast but it is also incredibility fast, flexible and unique. :)

I have some ideas and I know they are not very simple to do (I attached a drawing, I believe it's easier to explain) but let's go for them:

1- It would be nice if the hover feature could be built-in and just an enable/disable feature. If enabled, a box with the nearest values could show up for all the lines. This would save a lot of copy paste code if people have multiple charts.

2- The legend could be moved to the left side, the "Vertical Units" could go down and, together with the legend, the mouse points could be displayed together. On the left side it won't increase the needed size too much because there's already size reserved for the vertical units. The line color representation on the legend could also be reduced to not occupy too much space.

3- The horizontal units could also be moved to the left and up, so it doesn't use too much space on the bottom, this is particularly useful if you have multiple charts one under the other (of course, this is really not needed, maybe could have a way of choosing).

For the mouse hover, you will have multiple lines which not necessarily have the same X-axis, so it could have something like a "delta", which could be specified. It will show just the points if the line point is inside this range.