AddToZoneFromPluginHandlers

Using ADDTOZONE from certain plugin handlers

This document is linked to from the standard POD documentation

Warning! Take care when adding to zones from the following plugin handlers:

• commonTagsHandler
• beforeCommonTagsHandler
• afterCommonTagsHandler
• preRenderingHandler
• postRenderingHandler

Normally, adding to the same zone/id multiple times is fine - previous data is ovewritten to ensure content only appears once in the output. However, because these handlers are fired at the end of _renderZone() handling with Foswiki::Meta::expandMacros() and Foswiki::Meta::renderTML(), it is possible that multiple renderings of a particular zone (normally, only the first rendering should contain any content) will result in content appearing more than once.

See Tasks.Item9480 for background