WM_SIZE消息的wParam参数就包含了最大化和最小化标记: SIZE_MAXHIDE Message is sent to all pop-up windows when some other window is maximized. SIZE_MAXIMIZED The window has been maximized. SIZE_MAXSHOW Message is sent to all pop-up windows when some other window has been restored to its former size. SIZE_MINIMIZED The window has been minimized. SIZE_RESTORED The window has been resized, but neither the SIZE_MINIMIZED nor SIZE_MAXIMIZED value applies.
SIZE_MAXHIDE Message is sent to all pop-up windows when some other window is maximized.
SIZE_MAXIMIZED The window has been maximized.
SIZE_MAXSHOW Message is sent to all pop-up windows when some other window has been restored to its former size.
SIZE_MINIMIZED The window has been minimized.
SIZE_RESTORED The window has been resized, but neither the SIZE_MINIMIZED nor SIZE_MAXIMIZED value applies.