And just so I’m not leaving you in the cold, the problem should be solvable with a call to setup_postdata($post), which will set up all the other bits required to make “The Loop” switch over to the new post. It’s a two-line change; I’ve sent you a copy via e-mail.

The Customizable Post Listings plugin only sets $post; it does not set all of the other global values (among them $id, which is what get_the_ID uses) used by “The Loop.” Any plugin that uses the WordPress template tags (including In Series) is going to choke in one way or another when Customizable Post Listings calls apply_filters directly.

echo ‘<ul><li><a href=”/category/sideblog”>Arkiv</a></li></ul>’;
echo ‘<div id=”sidoblogg”><ul>’;
c2c_get_recent_posts(5,$format = “<li><h3>%post_title%</h3> %post_content%<p> (%post_date%)</p></li>”,$categories = ‘17′);
echo ‘</ul></div>’;

Yes, actually, I’m using to plugins to accomplish this:
First, “customizable post listings” (http://www.coffee2code.com/archives/2004/08/27/plugin-customizable-post-listings/) to generate a listing.
Secondly, it’s embedded in one of my favorites - “widgetize anything” (http://www.erik-rasmussen.com/blog/2006/11/30/widgetize-anything/).

The actual code within the widget:
echo ‘<ul><li><a href=”/category/sideblog”>Arkiv</a&gt:</li&gt:</ul&gt:’;
echo ‘<div id=”sidoblogg”&gt:<ul&gt:’;
c2c_get_recent_posts(5,$format = “<li&gt:<h3&gt:%post_title%</h3&gt: %post_content%<p&gt: (%post_date%)</p&gt:</li&gt:”,$categories = ‘17′);
echo ‘</ul&gt:</div&gt:’;

(not sure whether this will display correctly, but hopefully it’ll be enough to grasp the general idea).

Are you using a plugin to accomplish this? If so, can you provide a link to it? I need to understand how that page is generated in order to figure out what’s going on. In Series uses get_the_ID() (if present) or $post->ID (if not) to figure out the current post, then does a reverse-lookup to figure out which series data should be inserted. This lookup happens every time the_content() is called, so my first inclination would be that the source is somehow abusing or circumventing “The Loop” to get its results.

Thanks for the report. :)

However, when viewing part of the series, the_content expands in all posts, even those that are not part of the series. As I have a sideblog (based on excluding a category on the front page, then listing it in the sidebar), where the full posts are shown in the sidebar, the TOC expands in every single post there as well, when viewing an InSeries post.

Example (unfortunately in Swedish):
http://www.henriksjoholm.se/2007/04/17/i-kina/ is the first post in a series about China. When viewing this, you also see the TOC under the posts in the sidebar, heades “Bloggrannar” (blog neighbourhood).

Again, thanks for your great work!