Made it clearer that eventHolder is not the one that receives custom

Flot events


git-svn-id: https://flot.googlecode.com/svn/trunk@235 1e0a6537-2640-0410-bfb7-f154510ff394

API.txt

@@ -982,6 +982,12 @@ hooks in the plugins bundled with Flot.
    order wrong. The hook only gets one event, though (either for the
    overlay or for the static canvas).
 
+   Note that custom plot events generated by Flot are not generated on
+   eventHolder, but on the div placeholder supplied as the first
+   argument to the plot call. You can get that with
+   plot.getPlaceholder() - that's probably also the one you should use
+   if you need to fire a custom event.
+
 
  - drawOverlay  [phase 7]