I got difficulties to select the zoom range at the right of the graph. Try to select a zoom range from the middle to the full right. When leaving the graph zone at the right the zoom range is cleared and it's super difficult to select the last points. One solution is to add 'null' values at the end to get more space, but and I don't have place to put them to keep the good visibility of the graph.
Could it be possible to maintain the zoom range context before leaving the graph zone, or something else that could ease the selection?
Which version of dygraphs are you using? This was fixed in version 1.1.