Microsoft's ploy to transform Windows Phones into full-blown Windows PCs when connected to an external monitor may seem revolutionary, but it's nothing new. At least not in theory.

Canonical has been pitching an exciting vision of smartphone-PC convergence for years. The audacious Ubuntu Edge project achieved over $12 million in crowdfunding pledges because of this promise. Your phone could run a full operating system that functions like any other mobile OS in normal use. Dock it to a larger display, however, and you'd get a traditional desktop interface with more powerful applications.

This is the long-term vision of Ubuntu phone--but Ubuntu phones have been delayed time and time again. While the BQ Aquarius phone is now out in Europe, the rest of us are still waiting for the Meizu MX4. What's more, these phones don't provide "convergence" at all. That goal is still years in the future for Canonical. Canonical has shifted to touting Ubuntu phone's unique interface and design instead.

Ubuntu may have beaten Windows to the idea of phone-PC convergence. But it's something Microsoft is about to launch this year with Windows 10 phones, and in some ways, Microsoft's vision even outshines Canonical's.

Windows 10's "Continuum for phones"

Microsoft's bold move is made possible by a new feature in Windows 10 known as "Continuum for phones."

Continuum is the Windows 10 feature that allows a PC to switch between tablet-optimized and desktop-optimized interfaces when a keyboard is plugged in or removed. Continuum for phones is a feature that will let you plug a Windows phone into a larger monitor or dock and get a full Windows desktop powered by your phone.

Microsoft unveiled Continuum for phones at Build 2015. Connect a Windows phone to a monitor and a Windows desktop appears on that display. The phone can function as a makeshift mouse and keyboard, or you can connect physical mice and keyboards. Your phone functions as the brains, providing all the processing power you need to use applications in a desktop interface. You can even continue to use the phone's interface while it's plugged in, using both the phone interface and desktop interface at once, all powered by the same chip.

Theoretically, Windows 10's Continuum for phones could even one day use Miracast or a similar standard to wirelessly power a display without needing to plug your phone into a monitor.

Windows 10's "universal apps," which appear in smaller, finger-friendly form on phones, will scale up to their full desktop interfaces when you're using Continuum for phones. With Windows 10, this now includes the universal versions of Word, Excel, PowerPoint, and other powerful applications, and Microsoft's actively working to get developers to stock the Windows Store with more universal apps, including sandboxed versions of traditional Win32 and .NET-based desktop software.

In one fell swoop, Microsoft has potentially made Windows phones much more appealing to many more people. This is possible because Windows 10 for phones uses much of the same underlying technology as Windows 10 for PCs, especially the new universal apps. Even with Windows 8, both Windows 8 and Windows Phone 8 were different operating systems with different app platforms.

Canonical's vision of convergence and the reality of current Ubuntu phones

Meanwhile, in 2013 Canonical cast a spell over us with its own vision of "convergence" that would define Ubuntu for phones.

Ubuntu for phones was going to be a full version of the Ubuntu Linux distribution we all know and love, with a new version of the Unity desktop that could adapt to small screen sizes. A Ubuntu phone could be docked to a larger display and the Unity desktop would grow to provide a desktop-like interface, and those phone applications would run in floating windows with more powerful interfaces. All existing Linux desktop applications would run fine, too.

The dream has hit some stumbling blocks on the road to reality, however, though Canonical has been working on making the Ubuntu convergence happen.

That's why Canonical is creating its own Mir display server instead of the Wayland display server other Linux distributions use. That's why Unity 8 exists. Current versions of Ubuntu still use the Unity 7 desktop, but the experimental Ubuntu Desktop Next image uses a version of Unity 8. Canonical still has a lot of work to do on this interface, however--boot up Ubuntu Desktop Next and Unity 8 still thinks it's running on a phone, with references to smartphones in many places throughout the interface. It's taking Canonical a while to get there, and the main Ubuntu desktop with Unity 7 has seen few changes over the past few years as Canonical remains focused on Ubuntu phone and its cloud server aspirations.

Unity 8 is still used on those Ubuntu phones out there, but as mentioned, it has no convergence abilities. In February 2015, Canonical's Cristian Parrino addressed this:

"Convergence both in terms of a software platform that can operate on different form factors and also in terms of a device that can power a PC is very much part of our roadmap. The first BQ device is a smartphone, but it's not an Ubuntu Edge convergence play."

So it's on the radar, but it's not here yet. Canonical is struggling mightily to get the Ubuntu edition of the Meizu MX4 smartphone out so more of the world has a chance to actually use an Ubuntu phone.

For now, the official Ubuntu phone website doesn't even mention convergence at all. "Ubuntu introduces a new way to enjoy content and services on smartphones, without relying on traditional apps," it says, touting the scopes-focused interface. "Ubuntu Phone has been designed with obsessive attention to detail," Canonical goes on to promise. It's a new and unique interface, and that's great--but that's not why we were all so excited about Ubuntu phones in the first place.

Further reading: 5 more killer features Windows 10 should steal from Linux

Microsoft could still drop the ball, and Canonical could pick it up

So convergence is somewhere on Canonical's roadmap, and we could see it within a few years. But Microsoft will be launching its own version of this when Windows 10 launches--which could be in late July, if AMD's CEO has her dates right.

There are still ways Microsoft could drop the ball. Windows 10 for phones is based on the same software as Windows 10 for desktop PCs, and some of those Windows phones will use Intel CPUs. It's theoretically possible that traditional Win32 desktop applications could be installed on Windows phones and run in Continuum mode. But there's no indication Microsoft will allow this, and every indication suggest compatibility will likely be restricted only to Windows 10's new "universal apps." Even if Microsoft does allow desktop apps, only the sandboxed applications coming from the Windows Store are likely to be allowed--not any old desktop app you might want to run.

Ubuntu for phones puts no such limitations on its vision for convergence.

Imagine getting a powerful Ubuntu phone with an Intel chip and using it to run the Linux version of Steam, for example, or the existing ecosystem of powerful Linux desktop applications and command-line tools. That's the strength of open-source software. Whatever limits Microsoft places on this feature in Windows, we'll be able to bypass them and do whatever we want on Linux.

Either way, convergence is the future--and bringing an open-source version of that convergence for Linux users will be a win. But Canonical won't be the company to plant its flag here first. Microsoft just beat them to it.