rstudio/ggvis — pull request #225 by killkeeper (2014-07-26 21:32:09+00:00)
Title: Fixed a bug in mouseOffset() with Firefox, which lacks event.offsetX/Y properties

This commit addresses the issue with ggvis interactivity in Firefox, mostly with mouse clicking and dragging.
The current internal function mouseOffset() uses event.offsetX/Y which are undefined in Firefox, causing link_brush() to function abnormally.

This commit should fix that.