This toggle function allows you to exit, or re-enter, Layout mode once a layout has been created. If Model mode is the active mode when this toggle is selected, Layout will become the new active mode. If Layout is the active mode when the toggle is selected, Model will become the new active mode.

Bookmarking:

When a design file is saved, the system mode (Layout or Model) that was active at the time of the save is saved as well. Additionally, whenever a design file is loaded, it will open in the mode that was active when it was last saved. For instance, if a design file is saved while Layout mode is active, the file will open with Layout being the active mode the next time it is loaded.