What is the purpose of Windows style flags like WS_TILED and WS_ICONIC that are just renaming of others? (Windows/C++)

Question

I was looking at the various windows styles flags, and I noticed that a few flags are defined as such:

#define WS_TILED            WS_OVERLAPPED
#define WS_ICONIC           WS_MINIMIZE
#define WS_SIZEBOX          WS_THICKFRAME
#define WS_TILEDWINDOW      WS_OVERLAPPEDWINDOW

What is the purpose of defining new flags that are literally identical to other flags?

Answer 1

Its purpose is backwards compatibility. WS_TILED and WS_ICONIC probably date back to Windows version 1.

One of Microsoft's great burdens, once they put a #define or function in an SDK header file, they can never delete it again.