Which Windows version first allowed application windows to overlap?

Which Windows version first allowed application windows to overlap? Windows 2.0.

Windows 2.0, released on December 9, 1987, was the first Windows version to let application windows overlap and be resized. Windows 1.0 generally used a tiled layout, keeping application windows beside one another rather than allowing one to cover another.

The change made the desktop more flexible and familiar: users could move, stack, resize, minimize, and restore application windows. Windows 2.0 also introduced desktop icons, keyboard shortcuts, support for 16-color VGA graphics, and improved ways to run applications within the MS-DOS environment.

The overlapping-window feature contributed to a legal dispute with Apple, which argued that Microsoft had copied aspects of the Macintosh graphical interface. The case ultimately ended in Microsoft’s favor. Windows 3.0, released in 1990, became far more commercially successful, but it did not originate overlapping windows; that milestone belongs to Windows 2.0.