GM_registerMenuCommand resulting in duplicate menu items

[Morac]

I have a few scripts that add user script commands via the
GM_registerMenuCommand API call. Frequently I notice that these menu
items are getting duplicated in the user script command list. Only
the bottom-most one works so the other entries are bogus. I had this
problem under GM 0.8.1, but it also occurs under 0.8.2.

I notice there is protection against creating duplicate entries in
menucommanders.js, but for whatever reason that doesn't work. Either
that or multiple menu commanders are somehow getting attached to the
same window. I did notice that the number of objects in the
menuCommanders's array in browser.js did not match the number of open
tabs. Many of there objects contained null win objects or win objects
with missing locations. Basically they shouldn't have been there.
Since I never open more than 1 browser for the most part, there should
only be 1 menuCommander object anyway.

It seems to be a timing issue though since when I used the Javascript
debugger to trace through the code after I saw the issue, everything
worked fine.

I think one of the problems may be the way the menu command is added/
removed. The menu commander is added and attached on a contentLoad,
removed and detached on a contentUnload and attached/detached on an
onLocationChange evernt.

When going to a new page by following a link or typing an URL in the
address bar two events fire in the order specified: onLocationChange
and contentLoad. onLocataionChange detaches the menu commander from
the tab and then reattached it then contentLoad attaches it again. So
basically the menucommander is attached again when it's already
attached. This doesn't always result in two entries being added (not
sure why exactly), but since it's doing an appendChild for the same
exact element twice in a row to the same menu popup it's hard to tell
exactly what will happen in that case.

I think preventing the code from attaching an already attached menu
command might help with this problem.

[Morac]

Correction there should be one menu commander per tab, but I'm seeing
a lot more menu commanders than the number of open tabs. I have yet
to determine why that is, but I don't think that's related to the
duplicate commanders.

I think it has something to do with commanders being generated for
"about:blank".

[Morac]

Never mind about the duplicate menu-commanders. That only happens in
Nakamura loads. The duplicate menu items do happen in Firefox 3.5.3
though so it's not related.