I'm interested in learning more about Firefox's about:config configuration settings. I'm especially interested in why the developers have added the ability to create your own preferences for Firefox. It seems to be kind of similar to the Microsoft Windows registry, like how you can add your own custom values and suddenly windows behaves differently. But whenever I have configured the registry in windows, I have always had to follow tutorials, and I have always wondered how people were able to discover those registry settings. Did they have to have knowledge of the internals of the windows operating source code? Did they hack windows and discover that altering a certain registry setting, or adding a certain registry value, would cause the behavior to change? How did they come to understand such things? I recently edited the registry to change the right click menu in windows 11 back to the old windows 10 right click menu. I had to add a really long value into the registry, and it fixed it just like what I was used to in windows 10. But I have no idea how the person that wrote the tutorial knew to add that exact value. So, I'm wondering if the settings are hidden, and that's why you have to create them on your own? Or if by creating your own preference, one is programming the browser on some level... If so, what's the extent of programming that can be done by altering about:config and creating your own preferences? I have decent programming knowledge of javascript, C/C++, and python and all, but I don't understand something as complex as a browser, and why would you allow the user to create their own preferences, but I would like to. To clarify, I see there are preferences in about:config which are visible and can easily be configured, but I do not understand why there is a feature to add a setting. Is it just for developers of the browser? Is there ever a situation where a normal user like me might need to add their own preference? Can you recommend any manuals, documents, or books that I could read about it? Do you think it's something where I would just have to start reading the source code to eventually understand it? One last question: is it possible to disable certain javascript features using the about:config? Could I disable MutationObserver, for example? Or make it be undefined whenever a new tab is opened? Could I make it so that assigning to window.location has no effect? I'm interested to know these things and what is possible. Sorry for the long winded message, I doubt anyone will read it, but thank you if you read it, and thank you even more if you have answers. I have found the source code for firefox, but it seems to be a daunting task to just read the raw source code to get the answers I want.