The bug has been opened on https://bugs.launchpad.net/ubuntu/+source/gnome-panel/+bug/121243

"Binary package hint: gnome-panel

I am a heavy keyboard user and want to open for example firefox only by pushing my keyboard.
I configured my Ubuntu to show the panel menu when I push the Windows button.
Then I can go down the list with the arrow buttons and enter to open firefox.
But what I wanted to do after I can see the panel is push the "i" button to jump to "Internet",
then push the "f" button for "Firefox" and "enter" to open it.

But those accelerators sometimes work and sometimes not.
What works is navigating with the arrow buttons to the "Internet" menu,
pressing "T" jumps between "Terminal-Server-Client" and
"Thunderbird". This is good.
What doesn't work is opening the gnome panel and jumping directly to the "Internet" menu.

A second thing is that if the "Firefox" Starter in the "Internet" menu is highlighted it is not possible to jump back
to the main panel to select the "Graphics" panel and "Gimp" for example. Now it kills the whole menu.

As a summary, I want to be able to travel through the whole gnome panel tree only with character accelerators
and "escape".
..."