Comment 1 for bug 524179

Thank you for the bug report but the new behaviour of the icon is not a bug.
The new indicator application applet that Transmission and other applications are being ported to doesn't support (by design) right click. You can read more at https://wiki.ubuntu.com/DesktopExperienceTeam/ApplicationIndicators about what has driven developers to this decision.

I'm marking the bug as a Won't Fix, you should voice your concerns to the Canonical DX Team either by using IRC (#<email address hidden>) or by subscribing to the Ayatana Mailing List (though https://edge.launchpad.net/~ayatana).