Making an old unsupported extension work

[rosros]

I use CacheViewer, the current plug-in cannot be installed in Firefox
11.0.

I opened the old "cacheviewer-0.7b-fx.xpi" with 7-zip and extracted
the "install.rdf".

I edited the two lines:
<em:minVersion>5.0</em:minVersion>
<em:maxVersion>8.0</em:maxVersion>
To
<em:minVersion>5.0</em:minVersion>
<em:maxVersion>50.0</em:maxVersion>

(This should be enough to keep it working until Firefox 50.0).
Then I replaced the "install.rdf" in the compressed "cacheviewer-0.7b-
fx.xpi".
Installed the plug-in and it works fine.

Perhaps somebody could suggest the developers that the "maxVersion" is
not
really needed and checking it should be better removed from Firefox
code.