user32: Handle WM_SETICON message similarly to WM_SETTEXT.

dlls/user32/defwnd.c

@@ -677,8 +677,8 @@ static LRESULT DEFWND_DefWinProc( HWND hwnd, UINT msg, WPARAM wParam, LPARAM lPa
 
             USER_Driver->pSetWindowIcon( hwnd, wParam, (HICON)lParam );
 
-            SetWindowPos(hwnd, 0, 0, 0, 0, 0, SWP_FRAMECHANGED | SWP_NOSIZE |
-                         SWP_NOMOVE | SWP_NOACTIVATE | SWP_NOZORDER);
+            if( (GetWindowLongW( hwnd, GWL_STYLE ) & WS_CAPTION) == WS_CAPTION )
+                NC_HandleNCPaint( hwnd , (HRGN)1 );  /* Repaint caption */
 
             return (LRESULT)ret;
         }