This is the panel on the top right which contains a list of Service Items. The Service Manager manages what items are used in the service, and transfers the current Service Item to the Slide Controller when it is selected to be displayed.
An item that appears in the Service Manager. This item can be a song with a set of slides, or a set of images. Each plugin that needs to add items to the service, and display them, provides OpenLP with a customised Service Item.
OpenLP is built with a Plugin architecture. This basically means that OpenLP is made up of a bunch of components that "plug in" to OpenLP and provide certain features and functionality. Plugins themselves are "invisible", but they often provide key visible components like media items or menu items.