Hikari is a library for embedding Flash widgets into an Ogre screen overlay using the Internet Explorer Flash browser plugin. When I had first heard of this library I, like many others, had been using the somewhat antiquated CEGUI and were growing more frustrated by the day. At the time CEGUI had lost its main developer and the view among the Ogre community was that the project was dying and in need of replacement. Hikari is not the only, or even the first, to try to fill the void left by the then dying (but now reestablished) default GUI library package, but it is the only choice providing industry supported tools.
That said, I have had some sizeable stumbling blocks with Hikari. Many of these problems are merely results of fundamental incompatibilities with the Spark Engine. Hikari’s implementation creates an Ogre material and performs buffer blits between the Flash COM buffer and the Ogre material. This is all well and good, if it is done syncronously with Spark’s render thread, which it is not. So it seems Hikari will have to be altered to work within Spark’s rendering paradigm.
Overall I would give Hikari a 3.5/5 with a much higher possibility. One of its major caveats is that it uses the Internet Explorer browser plugin interface as opposed to something more portable like the NPAPI which would allow it to be cross-platform, though I hear this is something the developer is working on.