I’ve just got a quick idea for a new feature. Maybe in “Preferences” somewhere, there could be an option that says, “Page View Mirrors Compile Settings,” which is exactly what it says it is. It would look at the current Compile settings, the position of the document or group in question, and then when you switched into Page View, you would get a fairly WYSIWYG portrait — an “editable preview” as it were — of what the document you’re editing is going to look like once it goes through the Compiler. The utility of this, of course, is that unlike outputting to PDF and then opening in Preview, you could have, right there, an editable page preview. And of course, if the user then changed the formatting manually in Page View, Scrivener would be smart enough to “revert” to “standard” Page View instead.
While that is definitely a nice idea - and don’t think we haven’t bandied ideas about this sort of thing about ourselves - it’s not really possible from a technical perspective. There’s a plethora of problems, not the least of which is overriding fonts and formatting. With the rich text system, there would be no way to maintain the underlying formatting once you’ve edited even a little (and imagine where the user has selected a font in Compile that doesn’t support italics, and then finds all the italics are gone forever). The trouble is that there’s no way of only temporarily displaying different text attributes (other than colour). Now, that might be possible - I’ not sure - by creating an entirely custom typesetter class to override Apple’s one, but that would be a huge undertaking. And on top of that you have the issue of having to update the formatting every time the user drags the document to a new position, in cases where Compile is set up to use different formatting for different levels. Then Scrivener also has to deal with adding things such as title prefixes and suffixes into the text, and either not let you edit them, or try and feed back any edits to Compile… And so on.
It’s less of a hornet’s nest and more of a mutant-killer-slug’s lair (or something).
Compile is an incredibly complicated process as it is - and there are differences depending on the format chosen as well - and trying to apply it to individual documents at runtime would be a technical minefield.
That’s not to say it isn’t a good idea - just impractical at the moment. Maybe for version 5.0, though?
That said, I would like some better way of previewing the Compile settings in the nearer future, perhaps for version 3.0.