NeXTSTEP's interface (1988–1989) used subtle shading and depth for buttons and windows, creating a dimensional appearance. Its visual design pioneered the use of shading for depth in GUIs.

Microsoft's timeline:

CTL3D.DLL: Introduced circa 1991–1992, primarily for Windows 3.1 applications (not the OS itself). It added 3D effects to dialog boxes and controls but was optional for developers.

Windows 95: Introduced native 3D controls (e.g., recessed buttons, drop shadows) as the system-wide default in 1995, eliminating the need for CTL3D.DLL