Apple is working on a touchscreen operated desktop computer - an iMac Touch, if you will - a filing with US patent registers suggests.

Patently Apple, which scrutinises patents filed by the Mac maker, has this week unearthed a filing for a stand-mounted device that combines the touchscreen user interface of an iPad with iMac desktop functionality.

When in iPad-style entertainment mode, the as-yet-unnamed device employs iOS – the platform used in Apple’s tablet, as well as iPhones and iPods. Meanwhile, when it’s a desktop computer, plus a none-more-trad mouse and keyboard that’s needed, it runs on OSX.

Flipping between modes is a case of adjusting its elevation by lowering or raising the angle at which it rests. Apparently, you can even calibrate it so that it automatically switches operating systems when a designated level is reached.

It seems to be home to some interesting UI touches, too. Touch sensitive sides can detect when it’s being gripped. And there’s an accelerometer onboard too for Wii-style motion sensitive gaming.

So far, so good, eh? The chaps at Patently Apple were certainly impressed, dubbing it nothing less than a ‘dream machine’.

It’s certainly an interesting addition to the ever-growing Apple patent pile. But we’re not sure that it will get any further than that. There are a fair few reasons why it might be more prudent for it to remain a dream.

First up, is that there’s no mention in the patent whether the device can be untethered from its stand. If not, it loses the portability appeal that attracted people to iPads in the first place.

Strike two against it ever becoming reality is that were it to be removable from its base, Apple would effectively be cannibalising its own market. Why would it offer a device that’s part iPad and part iMac when the massed ranks of fanboys - and it seems even mass-market users - are clearly prepared to shell out for separate devices?