This tutorial instructs how to to create a new notification channel and a new notification type via a complete sample extension.
This tutorial instructs how to override portlets on the user profile page with your own templates.
This part is for administrators that instructs how to configure the file types associated with the application named as in "Open in Word" and set a new label via exo.properties.
To make the On-site notification (new feature of 4.2) work properly in a cluster environment, there are some extra steps to configure CometD Oort.
Check out the link above to see updates you need when setting up eXo Platform cluster.
This new section instructs how to leverage AJAX and HTML DOM Object when customizing your gadget in eXo Platform.