Rated 5 out of 5 stars
This is an excellent work-around in SeaMonkey 2.38 for bug #1175324. See https://bugzilla.mozilla.org/show_bug.cgi?id=1175324. Not only does it expose extension version numbers but also theme version numbers.
I call this a "work-around" because changes to the Add-ons Manager in the Toolkit might require ongoing changes to this extension.