Change Firefox Addon Support Version

Are you frustrated when you use Firefox’s nightly build and your latest Firefox browser simply cannot support your current addon?
Fear not, I am going to show you how to modify the addon that you wanted to install so that it can be installed on your Firefox browser.

1. Get any addons that you wanted to install from https://addons.mozilla.org/en-US/firefox/.
2. Download the addons but do not install it. You may do so by opening the link at another browser(simplest way).
3. You will find that the file extension of your addon is xpi.
4. Rename that file as a zip file. Example, rename firefox.xpi as firefox.zip.
5. Open the zip file with your File Archiver(Winzip, Winrar, 7-zip).
6. Locate a file called install.rdf(its at the root folder).
7. Open it with your notepad.
8. Locate something like this:
9. Edit the value inside em:minVersion and em:maxVersion to suit with your version of Firefox(Put the minVersion as low as possible and maxVersion as high as possible).
10. Save the file.
11. Rename it from .zip to .xpi
12. Drag your addon to your Firefox for installation.
13. Voila! Done.

Enjoy your latest Firefox version with your self-modified addon.