How to enable Google Toolbar in Firefox 5+

So far, I've denied upgrading Firefox, because the very useful Google Toolbar stopped working as from Firefox version 5. Due to the new strategy of Mozilla to release a new version of Firefox every 6 weeks, add-ons turn "incompatible", even if the API hasn't changed at all. But not upgrading Firefox exposures it to several security flaws, as Mozilla stops maintaining "old" Firefox versions.

I thought that Firefox would just deny executing the add on because of "some data". Something tells Firefox, "don't execute Google Toolbar". I raked up my profile's directory and found a solution. Here it is:

• Quit Firefox
  
• In the "extensions" folder of your profile's folder, there should be a folder named "{3112ca9c-de6d-4884-a869-9855de68056c}"
• There is a file "install.rdf"
• Open this file with an editor of your choice (in Windows, I recommend Microsoft Visual Studio (there are free versions, so called "Express Editions", out there))
• Find a phrase like this one: 4.0.*
• Just change "4" to your Firefox version number (should be 9 at the time of writing this blog), so it is: 9.0.*
• Start Firefox

At least for Version 9, this method worked. I will repeat this in every new version and once it fails, I will report it.