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#define INCL_WINMESSAGEMGR
 
BOOL WinInvalidateRegion(hwnd, hrgn, fIncludeChildren)
HWND hwnd;                /* handle of window with changed update region */
HRGN hrgn;                /* handle of the region to add                 */
BOOL fIncludeChildren;    /* invalidation-scope flag                     */
 
The WinInvalidateRegion function adds a region to a window's update region.
The update region represents the area of the window that needs to be
redrawn.
 
Parameter         Description
────────────────────────────────────────────────────────────────────────────
 
hwnd              Identifies the window whose update region has changed. If
                  this parameter is HWND_DESKTOP, this function updates the
                  entire screen.
 
hrgn              Identifies the region to be added to the window's update
                  region. If this parameter is NULL, the entire window is
                  put into the update region.
 
fIncludeChildren  Specifies whether child windows of hwnd are included in
                  the invalid region. If TRUE, child windows are included.
                  If FALSE, they are not.
 
Return Value
 
The return value is TRUE if the function is successful or FALSE if an error
occurs.
 
Comments
 
If the window style is WS_SYNCPAINT, the window is redrawn before returning
from the WinInvalidateRegion function.
 
If the window style is WS_CLIPCHILDREN and part of the window's update
region overlaps child windows that have the style WS_SYNCPAINT, those child
windows are updated before WinInvalidateRegion returns.
 
See Also
 
WinInvalidateRect, WM_PAINT
 
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