It is trivial to do this in Ubuntu 10.04. The question is specific to Ubuntu 12.04.

some pertinent references
(src: answer to What is the difference between indicators and a system tray?:
Here is the documentation for indicators:

Application indicators | Ubuntu App Developer
libindicate Reference Manual
libappindicator Reference Manual

also

• DesktopExperienceTeam/ApplicationIndicators - Ubuntu Wiki

ref: How can the application that makes an indicator icon be identified?
bookmark: How does one find out which application is associated with an indicator icon in Ubuntu 12.04?
is a serious question for reasons & problems outlined below and for which a significant investment has been made and is necessary for remedial purposes.

reviewing refs. to find an orchestrated resolution ...
(an indicator ap. indicator maybe needed)

This has nothing to do (does it?) with right click.

How can an indicator's icon in Ubuntu 12.04 be matched with the program responsible for it's manifestation on the top panel?

A list of running applications can include all processes using System Monitor.

How is the correct matching process found for an indicator?

How are the sub-indicator applications identified? These are the aps associated with the components of an indicators drop-down menu. (This was to be a separate question and quite naturally follows up the progression. It is included here as it is obvious there is no provisioning to track down offending either sub or indicator aps. easily.)

(The examination of SM points out a rather poignant factor in the faster battery depletion and shortened run time - the ambient quiescent CPU rate in 12.04 is now well over 20% when previously, in 10.04, it was well under 10%, between 5% and 7%! - the huge inordinate cpu overhead originates from Xorg and compiz - after booting the system, only SM is run and All Processes are selected, sorting on %CPU - switching between Resources and Processes profiles the execution overhead problem - running another ap like gedit "Text Editor" briefly gives it CPU priority - going back to S&M several aps. are at the top of the list in order: gnome-system-monitor as expected, then: Xorg, compiz, unity-panel-service, hud-service, with dbus-daemon and kworker/x:y's mixed in with some expected daemons and background tasks like nm-applet - not only do Xorg and compiz require excessive CPU time but their entourage has to come along too! further exacerbating the problem - our compute bound tasks no longer work effectively in the field - reduced battery life, reduced CPU time for custom ap.s etc. - and all this precipitated from an examination of what is going on with the battery ap. indicator - this was and is not a flippant, rhetorical or idle musing but has consequences for the credible deployment of 12.04 to reduce the negative impact of its overhead in a production environment)

(I have a problem with the battery indicator - it sometimes has % and other times hh:mm - it is necessary to know the ap. & v. to get more info on controlling same. ditto: There are issues with other indicator aps.: NM vs. iwlist/iwconfig conflict, BT ap. vs RF switch, Battery ap. w/ no suspend/sleep for poor battery runtime, ... the list goes on)

Details from:
How can I find Application Indicator ID's?

suggests looking at:
file:///usr/share/indicator-application/ordering-override.keyfile

[Ordering Index Overrides]
nm-applet=1
gnome-power-manager=2
ibus=3
gst-keyboard-xkb=4
gsd-keyboard-xkb=5

which solves the battery ap. identification, and presumably nm is NetworkManager for the rf icon, but the envelope, blue tooth and speaker indicator aps. are still a mystery. (Also, the ordering is not correlated.)

Mind you, it was simple in the past to simply right click to get the About option to find the ap. & v. info.

browsing around and about:

file:///usr/share/indicator-application/ordering-override.keyfile

examined:
file:///usr/share/indicators
file:///usr/share/indicators/messages/applications/
...

perhaps?/presumably? the information sought may be buried in
file:///usr/share/indicators

A reference in the comments was given to:
What is the difference between indicators and a system tray?
quoting from that source ...

Unfortunately desktop indicators are not well documented yet: I couldn't find any specification doc ...

Well ... the actual document
https://wiki.ubuntu.com/DesktopExperienceTeam/ApplicationIndicators#Summary
does not help much but it's existential information provides considerable insight ...