As it happens, I found a solution.
I was using the developer tools in Chrome to inspect the pages when I ran into an error message about line 1 on the page I was viewing.
I took a look at the HTML in the file "./html5output/portrait2.html", which was page 2 of the digital publication.
The first line looked like this:
- Code: Select all
<?xml version="1.0" encoding="UTF-8"?><html xmlns="http://www.w3.org/1999/xhtml">
The web server in question (due to be replaced) is running an old version of PHP that assumes <? is a way of invoking PHP. That makes it a problem here, rather than a problem with the HTML5 output from Quark. Since this server is due to be replaced with an updated server that properly uses <?php for its scripting tags, the problem will solve itself in due course.
In the meantime, an HTML5 document doesn't need that XML header. I removed the XML declaration from each of the portraitX.html files. After that, the error was gone and the digital publication viewer worked as intended.
As far as I can tell, the removal of the XML declaration hasn't affected the functions of the App Studio built-in menu, so the XML declaration is pretty much gratuitous. It doesn't hurt anything on a modern system but it's unnecessary.
That solves my problem, as I can just filter the pages to remove the XML declaration if I decide to try using the online publication.
As for the preview, while I know there's supposed to be a preview button, I never found it. Where is it located?