Firefox 6 has shipped, and with it of course come the notorious compatibility issues.
When developing a Firefox Addon, developers require to indicate a version series they want their addon to work with, such as 3.5-4.0. This gives the developer a window of opportunity to update their addon in the event an update in Firefox occurs that breaks it, so they can avoid being email bombed saying their addon doesn't work.
Luckily, these can easily be editable, and here's how:
Download the .xpi file of the addon.This can be done by finding the "+Add to Firefox" button, right clicking, and copying the short-cut into the address bar. After this, remove everything after *.xpi in the address. This is the direct link to the addon. A problem occurs when you try to go there directly, as FireFox instantly asks if you want to install it or not. To avoid this, you will need to use some sort of download manager, such as DownThemAll (easiest, just copy/paste the url into the downloader and it will pull up the file), or download the file using a different browser.
Once you download the *.xpi file, locate it on your hard drive. *.xpi files are really just re-named archives such as .rar and .zip. Right click the file, and open it with your favourite archiving software (7zip is free to download).
Inside, locate the file named install.rdf. This is a plane-text file, and can be open with Word, Notepad, or any text editor/word processor.
Find the following section near the top of the file(Make sure it says !--Firefox):
<!-- Target Application this extension can install into,
with minimum and maximum supported versions. -->
<!-- Firefox -->
Change the maxVersion number from 5.* as in the example above, to 9999. This will forever allow FireFox to use the addon, no matter what version it is, so long as no changes within FireFox disrupt the functions/requirements of the addon itself.
Save the file, and exit.
Exit the archive of the *.xpi file.
Open a new tab in Firefox, and drag the *.xpi file into the new tab window.
Firefox will then prompt you to install the addon.
This is a slightly tedious process, but it gives you an always-available file for the addon that will never be outdated.
Any questions or comments are welcome in the comment section. If you believe pictures are necessary, please indicate in your comment, and they will be added later.