IsWindow function (winuser.h)

Determines whether the specified window handle identifies an existing window.

BOOL IsWindow(
  [in, optional] HWND hWnd
);

[in, optional] hWnd

Type: HWND

A handle to the window to be tested.

Type: BOOL

If the window handle identifies an existing window, the return value is nonzero.

If the window handle does not identify an existing window, the return value is zero.

A thread should not use IsWindow for a window that it did not create because the window could be destroyed after this function was called. Further, because window handles are recycled the handle could even point to a different window.

For an example, see Creating a Modeless Dialog Box.

Conceptual

IsWindowEnabled

IsWindowVisible

Reference

Windows