Re: apparent acc bug in firefox

Hi Marco,

I'm one of the Polymer developers that Steve has been communicating with.
The issue it seems then is that Polymer is exposing these mouse handlers on
unexpected elements due to an interaction with the ShadowDOM polyfill and
Polymer's gesture system.

<too-much-info>
I implemented the gesture system to be a bit naive and add event listeners
in ShadowRoots to catch mouse events before they lose target information.
However, the ShadowDOM Polyfill has to add these listeners on the host
element, which will make that show up as "clickable" according to Firefox's
heuristic.
I'll have to add more cooperation hooks into Polymer to keep track of
elements that are explicitly interested in gestures to work around this
heuristic.
</too-much-info>

TL;DR: Polymer's gesture library is setting up listeners naively for a
gesture system, and we (Polymer) should make that smarter.