Transverse-mounted ribbon tweeters?

Has anyone seen a speaker with ribbon tweeters that are transverse-mounted? This would make the directivity pattern vertical instead of horizontal, which in almost all cases would be undesirable. However, if you were installing drivers to target one specific listening spot and the only variable was the listener's height, then a vertical directivity pattern would be more desirable I would think. Does anyone know if there are any detriments to installing and operating ribbon tweeters on their side? Are they sensitive to gravity? Thanks in advance,
You'd be widening the power response, narrowing the vertical response and widening the radiating surface horizontally...
Plus difficult to align the tweet with the next driver in line...
Why would you want to do that??
What greg said is true but I have heard a system with fountek ribbon set up so and it sounded fine.I will stick to vert but YMMV so try it if you like.
Greg, John--'narrowing' the vertical response? I think not.

Mounted vertically, ribbon tweeters have very little vertical dispersion because they're relatively tall. Horizontal dispersion is wider. When one mounts it 90 degrees off vertical, or horizontal, the vertical dispersion is now much greater than it was and the horizontal dispersion is narrower.
Apogee Acoustics has a moitor series where the ribbon tweeter (4in long) can be rotated so that the speeakers can be set on their side or up vertical. They sound pretty good, so they must have of overcome the above limitations. See the " Apogee Speaker Users Website" for more info.