Everyone has a list of customizations that they absolutely must make when they first set up a new computer. Maybe it's switching desktop environment, installing a different terminal shell, or something as simple as installing a favorite browser or picking out the perfect desktop wallpaper.
For me, towards the top of my list when setting up a new Linux machine is installing a few extensions to the GNOME desktop environment to fix a few quirks and allow it to better serve my daily use. I was originally a slow and reluctant GNOME 3 convert, but once I found the right combination of extensions to meet my needs, and found the GNOME Tweak Tool settings that changed a few other basic behaviors, I've been a happy GNOME 3 user for a few years now.
So here are a few extensions I've found myself simply unable to do without. This isn't meant as an exhaustive list, or one that is going to fit every user's needs. But for me, these extensions have worked well, and have quickly become indispensable.
For anyone who used GNOME 2, the Applications Menu will look familiar; it was the default application launcher for several years across many major distributions. For me, re-enabling the menu isn't just about a preference for the old launcher. I actually like the new launcher quite a bit as well. But in certain contexts, it's faster for me to find the application I was looking for by seeing it in a list grouped by application type and arranged with more emphasis on the name of the application than the icon. This is especially the case with rarely-used tools.
Applications Overview Tooltip
Most of the time, I've never even looked at the tooltips that describe an application when you hover your mouse over it. Sure, I know they exist, but I know what all of the applications I have installed are and what they do. Or at least, that used to be the case. After a few years of building up quite a collection of small indie games, I have to admit, I have a hard time remembering what each one is and what kind of gameplay it has. What makes matters worse is if you use Steam to install your game, you may not even get a custom icon installed with each game. And some applications with very similar names ("Awesome Game Pro Cool 1" and "Awesome Game Pro Cool 2") may have their names cut off, making it impossible to tell which is which.
So I've started writing custom tooltips for games I keep installed. Something as simple as "multiplayer real-time strategy" or "tower defense game" will remind me what it is before I launch. The Applications Overview Tooltip shows these tooltips for you in the applications overview, and lets you customize many things, like how long to hover over an icon before the tooltip appears. (I set it to be almost instant.)
Between all of the editing, systems administration, and data manipulation tasks that are a part of my day, my clipboard gets a healthy workout. I can't tell you how many times I've lost important text when shuffling around, grabbing one thing and accidentally replacing another, or simply wasting time copying a handful of things in rapid succession. Sure, I could dump the text in an editor, and several programs I use have application-specific clipboard histories, but Clipboard Indicator is my go-to tool for keeping track of various snippets of text as I write and edit, all sitting neatly under a little icon at the top of my screen.
I'm not a huge fan of the default Alt-Tab screen in GNOME 3. For one, grouping tabs by application isn't particularly helpful when pretty much every unique window I have open is a web browser with tabs arranged by window for particular contexts. In addition, I've grown to like the application overview screen you get when pressing the Windows super key, which has big, full portraits of your application windows. Coverflow solves this shortcoming of Alt+Tab with large snapshots of your applications, letting you see what each one is rather than squinting and hoping you picked the right window.
GNOME Shell Audio Output Switcher
Do you switch audio output frequently? For me, I find myself jumping between headphones, speakers, and Bluetooth devices all of the time depending on the context of where I'm using my computer, particularly with my laptop. I got tired of having to navigate through the preferences menu every time I wanted to change which output device I used, and GNOME Shell Audio Output Switcher simplified that process with a simple toggle that sits beneath my systems menu listing all of the attached devices.
I've mentioned GNOME Pomodoro before in my time management tools roundup, but it deserves mentioning here again. Essentially, it's a tiny timer that sits in the corner of your screen and helps your organize your day into productive chunks of time, allowing you to concentrate on a task for a limited period with a known end in sight. It's one of the top ways I stay productive in my day.
Be sure to grab the version from the project website or from your Linux distribution's software repository, as the version hosted on the GNOME shell extensions website is no longer up to date.
Multi Monitors Add-On
Once you've made the switch to using two or more monitors, it's really hard to go back. But by default, GNOME doesn't really make full use of additional monitors, at least in the way I would like it to. If you've hooked up a second monitor to your system before, you've probably noticed that the second monitor lack a top panel by default, as well as some other things that make you dependent on your primary monitor for controlling your system. The Multi Monitors Add-On fixes this by allowing you to toggle the panel, thumbnails slider, activities button, and application menu on your additional monitors, which for me, keeps me from whipping my neck back and forth just to use a menu with an active application on a different monitor.
Redshift is really much more than a simple shell extension, it's a tool to let you adjust the color temperature of your screen according to the time of day. It helps you to avoid eye strain and that inevitable feeling like you've turned into a zombie from staring at a screen for too long. It's similar to f.lux, which is arguably more popular but did not have a great interface in the Linux version when I last tried, and importantly to me, does not currently work on Wayland, which is the default compositor in Fedora 25. (Here's the trick for getting Redshift working in Wayland, by the way.)
Redshift's shell extension lets you customize color values, and turn it off when necessary, for example, if you're working with image editing and need to see images in their true color palette.
Personally, I am not a fan of the way that tray icons are handled in GNOME, cluttering up the bottom left-hand corner of my screen, and in some applications, accidentally capturing a click meant for something else. Fortunately, you can move them to a much more sensible location. TopIcons Plus take the icons from the legacy tray to the top right corner of your screen, giving you back more screen real estate and grouping icons for applications that insist on using them in a much more logical place. Personally, I like that you can then desaturate the icons themselves, changing them to the black-and-white of the rest of my top bar.
I'm not the first person to come up with a list of my favorite GNOME extensions, and I won't be the last. Other extensions I have seen a lot of love for, but which aren't exactly my cup of tea, include Drop Down Terminal (I prefer Guake), OpenWeather (I just don't need desktop weather updates), Media player indicator (all of my music comes from browser-based players which are incompatible with this extension), and Dash to Dock (which adds a ton of customization options, but I like the defaults GNOME offers just fine). But maybe they're perfect for you?
What's on your list of must-use GNOME extensions, and why?