I remember the days when I had multiple browser windows open so I could look at different sites at the same time. Now, I use Firefox's essential tabs feature because it's faster and easier use. Tabs have virtually eliminated the need for new windows. However, there are some times when tabs just don't fit the bill — you need a duplicate window open like when you're trying to read the description and the comments of an item in an online store and want to view both side-by-side.
You can go to 'File > New Window' but that just opens up your homepage instead of a copy (or clone) of the window you were viewing, and its a bother to copy the URL. Also if you have multiple home-pages, it could take a while to load, especially if you are on dialup.
Unlike cloning a sheep, cloning a window is quite easy thanks to Firefox's wonderfully handy extensions! You can download the "Clone Window" extension from the author's website or from the Mozilla Extension Room.
Once you've got Clone Window installed, opening a new window will clone the first tab from your existing window. You should go to "Tools > Extensions> Clone Window" and click the Options button to change the settings to personalize the extension to fit your needs. There you can select which option you prefer when you select 'New Window'. You can choose between the default action, a blank window, your homepage or homepages, or a cloned window (an exact copy of the window you are on).
Even though this is the Clone Window Extension, it could really be called the Clone Window and Tabs Extension because it can modify the tabs behavior too. Just like the new window options, you can choose between the default action, a blank tab, the home page tab, or a cloned tab.
You may only use this extension a few times, or you may use it all the time, but it will take away just one more of those tedious tasks.
Pablo