The IsZoomed function determines whether a window is maximized.
BOOL IsZoomed(
HWND hWnd // handle to window
);
If the window is zoomed, the return value is nonzero.
If the window is not zoomed, the return value is zero.
Windows NT: Requires version 3.1 or later.
Windows: Requires Windows 95 or later.
Windows CE: Unsupported.
Header: Declared in winuser.h.
Import Library: Use user32.lib.
Windows Overview, Window Functions, IsIconic