When I manually update (i.e. firefox.exe example.xpi) an extension (e.g. Status-4-Evar 2011.07.20.21) VSW alerts:
"ViewSourceWith can be easier to use from a toolbar button, do you want to add it?"
And resets the viewSource.xml file (i.e. wipes settings) in the profile directory.
The bug does not occur with every extension I manually update.
Windows XP SP3