In this animation I've interpreted Outline, Slide Sorter, and Full Slide modes as workspaces. Opening the Workspaces menu displays each of the default workspaces plus an area to save user-generated spaces. The bottom section indicates which panes are currently open (Thumbnails, Slide, Notes, etc.).

The dividers would be adjustable and each pane has an 'X' button to minimize it. To restore a pane, select it again from the Workspaces menu. The currently active workspace is indicated by an arrow.