[[Dive into Mozilla]] > [[Dive into Mozilla Day 5]] > Modifying Firefox using an Extension Lab
'''...in progress...'''
=Introduction=
In this walkthrough, the [[Dive into Mozilla Modifying Firefox Lab|previous lab]] we will explore the process of making made a small change to the behaviour of Firefoxby modifying the browser's source code. In so doing, this lab we'll learn explore how to go from achieve the same effect using an idea for a top-level UI feature change, to searching and studying '''extension''' rather than modifying the code, to making and testing this change. The goal of this exercise is to give you confidence in order to try similar things on your own, expose you to some helpful techniques, and to highlight the importance of using existing code in open source and Mozillatree.
=The goal of this exercise is to expose you to Firefox extensions and to show you how to modify or extend the browser without changing it'What': change s source code directly. Some thought will also be given to the way new tabs get created two methods of doing this (i.e., in Firefox= the tree vs. as an extension), comparing their advantages and disadvantages.
Currently, when you create a new tab in Firefox, it is appended to the end of the list of currently opened tabs. However, often one opens a tab in order to work on something associated with the current tab, that is, if I=The 'm working in tab 6, IWhat'd like : change the way new tab to be placed at position 7 and not 21 (assuming there are 20 tabs open).get created in Firefox=
Here are As was [[Dive into Mozilla Modifying Firefox Lab#The_.27What.27:_change_the_way_new_tabs_get_created_in_Firefox|previously the steps case]], our goal is to reproduce this modify Firefox so that new tabs are created (commonly shortened to '''STR''', especially in [https://bugzillai.mozillae.org bugzilla]positioned):beside the current tab instead of being appended to the end of the list.
# Start Firefox and open a series of tabs (i.eHowever, unlike last time where we modified tabbrowser.xml directly, CTRL+T)# Move to this time we will '''overlay''' our changes onto the first tab# Open another new tab browser at runtime, and notice its placement in alleviate the list (ineed for any direct changes to the code.e This is possible using '''extensions'''., it should be last)
=The 'Where': finding the right spot to make the changes=
