# Master/Details block

Master/Details is a pattern used throughout the UI world. It consists of a list or a tree ('master') and a set of properties ('details') driven by the selection in the master. Eclipse Forms provide the implementation of the pattern as a useful building block with the following properties:

- While details part is created, master part factory method is abstract and must be implemented by the subclass

- Master and details parts are children of the sash form and the ratio of the form space allocated for each can be changed by moving the sash.

- Through the nature of the sash form, master and details parts can be organized horizontally or vertically in the form.

The idea of master/details block is to create a tree or a table section that fires the selection notification via the managed form. If the details part can handle the selected object, it should switch to the page for it and display properties. When building on top of the provided master/details block, subclasses should:

- Create the master part (the one that drives the details)

- Contribute actions to the form tool bar (consumes upper-right portion of the form in the title area)

- Register details pages, one for each distinct input that can arrive from the master part