UpdateWindow function (winuser.h)

The UpdateWindow function updates the client area of the specified window by sending a WM_PAINT message to the window if the window's update region is not empty. The function sends a WM_PAINT message directly to the window procedure of the specified window, bypassing the application queue. If the update region is empty, no message is sent.

Syntax

BOOL UpdateWindow(
  [in] HWND hWnd
);

Parameters

[in] hWnd

Handle to the window to be updated.

Return value

If the function succeeds, the return value is nonzero.

If the function fails, the return value is zero.

Requirements

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-draw-l1-1-0 (introduced in Windows 8)

See also

ExcludeUpdateRgn

GetUpdateRect

GetUpdateRgn

InvalidateRect

InvalidateRgn

Painting and Drawing Functions

Painting and Drawing Overview

WM_PAINT