How to use firefox "hello world" sample extension?

I downloaded this Firefox sample extension from mozilla.org, I modified the file install.rdf and changed maxVersion value to 3.6.10 (also tried 3.6.*, 100 and *) and I added a new string with name "hello world" and the value is the path where the folder of the sample extension is to HKCU (also tried HKLM)/Software/Mozilla/Firefox/Extensions/ into the registry.

I start Firefox, go to Tools > Addons, and it says it needs to restart, I restart and go there again and the plugin appears but says "Not compatible with Firefox 3.6.10", and every button appears disabled. Also removing the registr开发者_如何学Goy key and folder doesn't uninstall it.

Is there something else I have to change to use the hello world sample in Firefox 3.6.10?

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Update 2018

This sample extension was created in 2000s and Firefox switched to a radically different extension system called "Web Extensions" in 2017. The old extensions will not work in the current versions of Firefox and have to be rewritten completely.

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The easiest way to start developing an extension is putting a "pointer" file in the extensions folder in the profile directory. I wouldn't touch the registry method until the deployment moment.

Thanks for reminding me to update the example extension. Updated it now.

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Basically, the best way to use an extension is to package the addon in .xpi format. Then you just have to open this addon with Firefox. Note:To make an .xpi , take all the contents of helloworld like content,locale,skin,install.rdf,chrome.manifest etc and try to zip it but change the extension to .xpi instead of .zip. Otherwise u can just rename ur helloworld folder to helloworld@xyz.com and then copy this folder into C:\Users\"OS user name"\AppData\Roaming\Mozilla\Firefox\Profiles\h31hcfq9.default\extensions and then restart ur browser. Also, it would be best to learn about addon development with this Basic tutorial on addon development

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The procedure to create sample firefox extension can be found on this link. This tutorial explains how to create a Firefox extension to find all links in the current web page, highlight those which have a target attribute and alert you how many links it found.