IsHungAppWindow function (winuser.h)

[This function is not intended for general use. It may be altered or unavailable in subsequent versions of Windows.]

Determines whether the system considers that a specified application is not responding. An application is considered to be not responding if it is not waiting for input, is not in startup processing, and has not called PeekMessage within the internal timeout period of 5 seconds.


BOOL IsHungAppWindow(
  [in] HWND hwnd


[in] hwnd

Type: HWND

A handle to the window to be tested.

Return value

Type: BOOL

The return value is TRUE if the window stops responding; otherwise, it is FALSE. Ghost windows always return TRUE.


The Windows timeout criteria of 5 seconds is subject to change.

This function was not included in the SDK headers and libraries until Windows XP Service Pack 1 (SP1) and Windows Server 2003. If you do not have a header file and import library for this function, you can call the function using LoadLibrary and GetProcAddress.


Requirement Value
Minimum supported client Windows 2000 Professional [desktop apps only]
Minimum supported server Windows 2000 Server [desktop apps only]
Target Platform Windows
Header winuser.h (include Windows.h)
Library User32.lib
DLL User32.dll
API set ext-ms-win-ntuser-window-l1-1-3 (introduced in Windows 10, version 10.0.10240)

See also