Long-time users of Joomla are quite familiar with content plugins. When you want to take some user-entered text and reformat it into something else, there’s nothing quite as handy as having a content plugin ready to do your bidding.
However, Joomla 1.5 brought some subtle behavior changes. In Joomla 1.0, content plugins act on both articles entered through the Article Manager, as well as HTML entered in user created modules. When a Joomla 1.0 content plugin is recoded for 1.5, the original effect still takes place on content items, but module output is left unchanged.
What happened? Content plugins in Joomla 1.5 are designed to only act on articles managed through the Article Manager. This will seem inconvenient to people used to the old behavior, but there is a good reason for this change. While many content plugins reformat user-entered HTML, others add markup near the article title or just after an article is output. Also, some content plugins are designed to do additional tasks when articles are saved. These actions do not make sense within the context of a module, so content plugins no longer run on them.
While this good in that it enforces consistency, it also poses a problem. Now that content plugins only work on articles, how do you reformat markup coming from modules? Fortunately, there are a couple of workarounds in Joomla 1.5 achieving similar (if not better) results.