The motion sensor in the Leap Motion Controller works in a similar fashion to Microsoft's Kinect, allowing you to use hand gestures to control a Windows PC or Mac. Now that touch-sensitive screens have become commonplace on phones, tablets and laptops, HP is clearly hoping to take the next step forward in interface technology by being the first manufacturer to incorporate the Leap Motion technology in a laptop. (See also: What's the best laptop you can buy in 2014?)
For the most part, the Envy 17 is a fairly conventional 17-inch laptop. This 'special edition' model is priced at £1199 with a Haswell-generation Intel Core i7 processor running at 2.2 GHz, a giant 12 GB memory and 1 TB hard drive. There's even room for a built-in DVD drive.
HP Envy 17 Leap Motion SE: graphics
As well as Intel's HD 4600 integrated graphics the Envy 17 also includes an nVidia GeForce GT 750M graphics processor that provides modest gaming capabilities.
If you're after a more affordable large-screen laptop, then the standard Envy 17 is still available without the Leap Motion sensor, and a better value Core i5 processor, for £799.
A 17-inch laptop such as this is obviously not meant to be carried around in a briefcase or backpack, but its 3.4 kg weight is not unliftable and it can easily be carried from room to room at home or at work.
Battery life is rather below par though, giving us just 3 hours 45 minutes of streaming video, that using the more economical integrated graphics. We've seen 17-inch laptops with better battery life, including 5 hours from Dell's new Inspiron 17-7000 model, but the Envy 17 isn't going to stray far from a mains socket so that's probably not a deal-breaker for many people.
HP Envy 17 Leap Motion SE: system speed
System speed is something of a mixed bag. The general-purpose PCMark 7 places due emphasis on storage performance, and the use of a 5400 rpm hard drive here meant that the Envy 17 managed a score of just 3300 points.
That's not a bad score by any means, but a faster solid-state drive would typically push that well past the 4000-point mark.
The more specialized Home and Work suites in PCMark 8 produce similar results, with scores of 2867 and 3000 points respectively that are respectable but not outstanding.
Even using the Microsoft Windows 8 'fast-start' option (actually a standby mode), the Envy 17 took a full 30 seconds to boot into the Start screen, followed by another good 15 seconds of cursor-spinning before it was ready to start launching apps and get to work.
But, once it had got going, the Envy 17 was perfectly capable of tackling a wide range of tasks, and its large screen, memory and hard drive mean that it's well suited to demanding work such as photo- or video-editing. (See also: 20 best budget laptops of 2014.)
HP Envy 17 Leap Motion SE: display
The 1920 x 1080 display is bright and colourful, with horizontal viewing angles that come close to a full 180-degrees. The vertical viewing angle is a little more limited – around 140-degrees – but the Envy 17 will still work fine for presentations or simply watching streaming video at home.
And while the Envy 17 isn't intended as a gaming rig its GeForce GT 750M graphics could manage a respectable 52 fps when running our Stalker gaming test at 1920 x 1080 resolution. This laptop will be fine for more than occasional gaming sessions.
But, of course, the real attraction of the Envy 17 is that new Leap Motion sensor.
The sensor – which includes a fingerprint reader as well – is a slim plastic strip that is 120 mm in length, and sits just below the right-hand edge of the keyboard. The technology is certainly impressive, and the sensor is precise enough to detect even small movements of all ten of our fingers on both hands.
But, as we found when testing the standalone Leap Motion Controller earlier this year, there are few apps currently available that use gesture-recognition particularly well.
Leap Motion's AirSpace Store does include some fun games and musical apps, as well as some apps that can use gestures to control Windows itself. You might be able to show off by using gestures to browse through your holiday snaps or a set of presentation slides, but that may not justify the £1200 price tag.
Some of the most interesting third-party apps use gesture control for 3D modeling and visualization, so there might be a specialist market in some design and scientific fields, but we're still some way from Tom Cruise flicking holographic screens around in Minority Report. (See also: What's the best laptop you can buy in 2014?)