When using "Sort By Name" on the top level bookmarks folder the static menu items are sorted as well

When I try to sort my root bookmarks folder (folders/bookmarks visible when
clicking on the Bookmarks menu item), what I would consider the "static" menu
items (e.g. "Bookmark this page", "Bookmark all tabs", etc.) are sorted along
with the bookmarks. This behavior is maintained until I restart Firefox at
which point the static menu items are restored to their original positions. When running Firefox in safe mode this issue does not occur. Only after installing XMarks does this issue happen

Steps to Reproduce:
1. Install XMarks
2. Click on Bookmarks menu item
3. Right click "Sort By Name"
4. Static menu items are now sorted

Actual Results:
Here is what my Bookmarks menu looks like after sorting:

Recent Tags >
Recently Bookmarked >
----------------------
Arts & Crafts >
Cycling >
...
Travel >
Bookmark This Page
Bookmark All Tabs...
Organize Bookmarks...
----------------------
Bookmarks Toolbar >
----------------------

Expected Results:
Here is what my Bookmarks menu looks like after restarting Firefox (and what
should happen when sorting by name):

Bookmark This Page
Bookmark All Tabs...
Organize Bookmarks...
----------------------
Bookmarks Toolbar >
----------------------
Recent Tags >
Recently Bookmarked >
----------------------
Arts & Crafts >
Cycling >
...
Travel >