Complex sentence: A window can be iconized by double clicking its titlebar, dragging this one onto an empty spot on the bar, or from one of its menu items, and restored by double clicking its icon or dragging it outside of the bar.
Split into simpler sentences: A window can be minimized by double-clicking its title bar, dragging the title bar one onto an empty spot on the bar, or by issuing a command from one of its menus. A minimized window is restored by double-clicking its icon or dragging it outside of the bar.