Catalog(s)
The large right-central part of the Main window may show one or more Catalogs.
A Catalog provides an overview of:
Objects shown in a Catalog can be double-clicked, dragged to an existing map window, dragged to a pixel information window, dragged to an operation in the Operation-tree or the Operation-list, or dragged to a text box in a dialog box.
Furthermore, when you click an object with the right mouse button, a context-sensitive menu appears which contains all relevant actions/operations for that object.
For more information, see also How to use a Catalog or Main window : Catalog.