The $3,000 HoloLens developer units are due to arrive within the next few weeks, but it seems that a few of them have been in the hands of closed beta testers since January, and some information about the devices has leaked courtesy of Twitter user WalkingCat.

The leaked material includes lots of information about a new, not yet publicly demonstrated holographic app called Actiongram (codenamed Project Burbank). The beta testers have been given an early version of this app and are on the hook to create a bunch of videos over the next ten weeks that will presumably showcase the app itself and HoloLens in general. Actiongram is a mixed reality app that overlays videos and animations on the real world, enabling, for example, Deal With It sunglasses to drop down onto a real person's face, or an astronaut to bounce around on your sofa, or all sorts of other things.

The leaked materials include a handful of as yet unreleased pieces of HoloLens information. A video that's used to introduce the beta testers to the platform includes a look at the holographic iteration of the Windows Start menu. An accompanying document describes a Bluetooth clicker peripheral that can be used to interact with holograms—presumably a more convenient alternative to Microsoft's index finger "tap" gesture that has previously been used in demos—and also includes a screenshot of the holographic iteration of the Photos app used in Windows 10.

The documentation also says that Microsoft will be publicly unveiling Actiongram on February 29. On this date, Microsoft will also announce when devices will first start shipping to developers. Actiongram itself is in a two-stage closed beta, with the first stage ending at the end of March and the second closing at the end of May prior to an open beta that runs from August 6 until October 29.