In a recent WebCompat bug, we discovered an issue related to the event retargeting with
ui.mouse.radius.enabled == true. Full details, including retargeting logs and a frame dump, are available in the linked WebCompat bug.
The site in question implemented a CSS-only multi-level navigation, with the markup resembling something like
<ul><!-- submenu <li>s --></ul>
display: hidden; by default, but they're set visible if the parent
:hover. Unfortunately, neither the
<li> nor the
<span> had any indication that it was clickable - no pointer cursor, no
role="button", ... - and in this case, this causes the menu to be hard to use on Firefox for Android. Trying to expand the "Two" submenu pretty much always results in "One" being clicked instead.
Unfortunately, I assume that neither this implementation, nor the lack of "clickable" indication, are all too rare, and this might have a relatively high number of slight-annoyances issues attached to it.
One possible idea is to add elements with
mouseover handlers and elements with
:focus styling to the list of good targets for event re-targeting. This would make this site usable, and probably also resolve a couple of other issues. However, I also assume that this has some downsides attached, so I'd appreciate the feedback of someone with more knowledge here. :)
(Searchfox told me to file in
Core :: Layout for
layout/base/PositionedEventTargeting.cpp, but this might just as well be something for
Core :: DOM: Events, not sure.)