[Usability] HIG clarification: single click on notification area icons?

[John Spray <jcs116 york ac uk>]

Hi,

Looking at the HIG at [1], I'm a little confused about whether
anything's supposed to happen when a user single-clicks on a
notification area icon (NAI).  Is it to be that a single click should do
nothing, or is the HIG leaving this up to developers?

It would seem a little unnecessary to force users to double-click when
the single click is unused.  I also find a NAI which responds only to a
double click to have poor discoverability: I left click, right click,
and then the icon seems to be dead to me when nothing happens.

Looking at the "Mouse Interaction" section of the HIG, I see that the
single click is supposed to be reserved for selection, where the double
click is for activation.  Since there is no meaningful concept of
selection of a NAI, this surely cannot be usefully applied to them?

The reason I'm thinking about all of this is epiphany bug #131012 (at
[2]): the download icon which accepts only a double-click as input and
ignores all single clicks.

Regards,
John Spray
(jcs116 york ac uk)

1.
http://developer.gnome.org/projects/gup/hig/draft_hig_new/desktop-notification-area.html#desktop-notification-or-appletposed 
2. http://bugzilla.gnome.org/show_bug.cgi?id=131012