SetParent function

Changes the parent window of the specified child window.

Syntax

HWND SetParent(
  HWND hWndChild,
  HWND hWndNewParent
);

Parameters

hWndChild

Type: HWND

A handle to the child window.

hWndNewParent

Type: HWND

A handle to the new parent window. If this parameter is NULL, the desktop window becomes the new parent window. If this parameter is HWND_MESSAGE, the child window becomes a message-only window.

Return Value

Type: Type: HWND

If the function succeeds, the return value is a handle to the previous parent window.

If the function fails, the return value is NULL. To get extended error information, call GetLastError.

Remarks

An application can use the SetParent function to set the parent window of a pop-up, overlapped, or child window.

If the window identified by the hWndChild parameter is visible, the system performs the appropriate redrawing and repainting.

For compatibility reasons, SetParent does not modify the WS_CHILD or WS_POPUP window styles of the window whose parent is being changed. Therefore, if hWndNewParent is NULL, you should also clear the WS_CHILD bit and set the WS_POPUP style after calling SetParent. Conversely, if hWndNewParent is not NULL and the window was previously a child of the desktop, you should clear the WS_POPUP style and set the WS_CHILD style before calling SetParent.

When you change the parent of a window, you should synchronize the UISTATE of both windows. For more information, see WM_CHANGEUISTATE and WM_UPDATEUISTATE.

Unexpected behavior or errors may occur if hWndNewParent and hWndChild are running in different DPI awareness modes. The table below outlines this behavior:

Operation Windows 8.1 Windows 10 (1607 and earlier) Windows 10 (1703 and later)
SetParent (In-Proc) N/A Forced reset (of current process) Fail (ERROR_INVALID_STATE)
SetParent (Cross-Proc) Forced reset (of child window's process) Forced reset (of child window's process) Forced reset (of child window's process)
 

For more information on DPI awareness, see the Windows High DPI documentation.

Requirements

   
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

See Also

Conceptual

GetParent

Reference

Windows