If neither render nor redirect is called, the default is to call render for a template of the same name as the action. There is currently no way to add to the explicit actions (render and redirect). In the case where a multi-pane single-page app is having panes refreshed, each refresh is a logically separate RJS action, but currently, all must be called from a single render, which subverts this logical separation.
This ticket is for a patch that adds an add_default_render method to Controller::Base, which appends a passed block to @default_render_chain. If no render or redirect occurs, the blocks on this array get called in order until one returns true, and only if none do, the current default render applies.
In this way a plugin can define a method (in my case "refresh") which replaces the default render operation with a render :update that calls all the refresh blocks. That way each refresh block is properly isolated from the others.
This was discussed in rails core around 2007/09/25.
