I really hope this helps someone!
I've been using Windows for 20 years!!!
I used a Mac for the first time on a temporary assignment recently and loved it (want one now - they're like silk!)
So I started thinking about Linux OS (because Mac is based on unix isn't it?), and in particular I loved this behaviour.
So I came across Fedora (20) and just "chose" it (without looking for this hotspot behaviour actually) and was really pleased to find it had a top-left hotspot active by default.
So I started learning Linux/bash/cli and most solutions on Stack O F and whilst googling for answers were for Ubuntu and never worked on Fedora!
Eventually, looking for an extra hour for "Fedora only" solutions time after time wore me out (4 days!!!) so I ditched Fedora (nice, slick, solid - just not as popular therefore not as well supported in the "googling for answers" sense) in place of Ubuntu!
Man, was I disappointed about this hotspot thing!
Ubuntu 14.04 didn't have this feature straight out of the box, nor was it configurable!
I figured that I could "skin" my desktop so I googled "ubuntu touch corner screen like fedora" and found this web-page
Here it said that Gnome Shell 3 had this behaviour and it was available in the "Ubuntu Software Centre" (which is on the Ubuntu dock by default)
If you want to install the GNOME Shell on Ubuntu, just head into the Ubuntu Software Center and search for GNOME Shell. Install it, then log out of your system—you should see a small gear icon on the login screen, which you can then use to boot into the GNOME Shell instead of Unity.
I tried out 3 of the 4 gnome shells from this package and found them to be a backwards step, as in "going back in time" backwards!
There's nothing wrong with Gnome shell for those who love it - that's just my 10 minute appraisal after using Ubuntu Unity for 24 hours and switching to Gnome for a quick appraisal! The webpage above also showed it to be lacking in features and a touch irritating
About the Gnome Dock (and why it's outdated):
Not only is it annoyingly hidden away, but adding more icons shrinks it down, à la Mac OS X, as opposed to making it scrollable like Unity's. This doesn't seem like a problem at first, but it gets a lot harder to use if it shrinks down far, and it starts shrinking down long before it fills the entire side of the screen...
Compare this to the Unity dock:
Unity's dock is sadly not movable from its left-hand position, which is very annoying (Isn't Linux is supposed to be super customizable?). However, despite this annoyance, it does have some nice Ubuntu integration that you don't get in the GNOME Shell—for example, you can right-click on Thunderbird's dock icon to compose a new message or browse your address book
and more Unity goodness...
The Dash: You can access Unity's application launcher—called the Dash—by hitting the Windows key on your keyboard or by hitting the Dash icon at the top of Unity's dock. The Dash is a panel that replaces the drop-down menus of classic GNOME. From it, you can search through all your installed apps, settings, files, or even music from one location. You don't need to click on the search box either—just open up the Dash and start typing. It'll even show you apps that you don't have installed, but that you can download from the Ubuntu Software Center, which is convenient. By default, the Dash searches through your apps, though you can hit the icons across the bottom of the Dash to search through files or music through their own "lenses". This is a pretty nice feature, and it makes the Dash pretty versatile
Most people would probaly say I'm a Unity fan but I'm not - I'm a fan of clever design and good UI/UX - and to be honest I've only been using it for around 24 hours and reading this comparison really helped me decide and I started to get cold feet (change my mind) about this whole Gnome shell thing!
So then I thought "this thing's called Ubuntu Unity right - why not try "Ubuntu Unity hotspot" in google" and that led me to this thread real quick!
So I started reading the solutions and saw the nerdy code idea and thought ... nah!
I like coding but I'm rubbish at it and this linux bash/cli thing is pretty confusing:
"root, sudo, chmod, chown, 777, 644, owxr, /, ~/, $HOME, ls, vi, pwd, as root, never login as root, owner of apache2, PERMISSIONS (great but confusing), yum, rpm, apt-get" etc, etc.
I'm sure you get my point!
Anyway, that made me try the CompizConfig solution and I got some sort of error whilst installing and that made me think it wouldn't work so I went on to install Unity Tweak Tools.
I followed the instructions and blam...it worked!
Go to 'Window Manager' -> 'Window Spread' and choose 'Hot Corners' tab.
You can install it from the Ubuntu Software Centre and you can access it from the "Dash" by clicking the top icon on the dock (default) or by hitting your Windows/Start button.