In the Manual (F1), a button at the start of the breadcrumbs hides or shows the table-of-contents sidebar, and so does Ctrl + B. The choice is remembered. While the sidebar is hidden, moving the mouse to the left edge shows it over the page until the mouse leaves it.

-presentation and -fullscreen now also apply when the file is opened in an already running SumatraPDF. Two new DDE commands do the same: [Presentation("<file>")] and [FullScreen("<file>")].