I know in the past enTourage has told me that displaying a book in landscape in and of itself isn't the challenge, but rather the annotating and annotations. Which is probably why it's taking so long to get this feature out the door (enTourage has shown a history of holding back features that simply aren't working reliably enough - a subjective standard, true, but one they've set for themselves).

Still, thinking back to my days in university and the reading I did on computer graphics, it should be a simple matter of applying a rotational matrix to coordinates and input. Easy to say from my comfy armchair, though

Nevertheless, I'd really like to get this feature