You customize the XML-based CUIx file with the Customize User Interface (CUI) Editor to create new commands, user interface elements, and workspaces.
The Customizations In pane is used to navigate the different user interface elements that are in the loaded customization files.
The Command List pane is used to create and locate commands that are contained in the loaded customization files.
The Dynamic Display pane controls the display of additional panes that respond to the item that is selected in either the Customizations In pane or Command List pane.