private void UpdateStyles() { // To show style changes, the non-client area must be repainted. Using the // control's Invalidate method does not affect the non-client area. // Instead use a Win32 call to signal the style has changed. User32.SetWindowPos(MdiClient.Handle, IntPtr.Zero, 0, 0, 0, 0, Win32.FlagsSetWindowPos.SWP_NOACTIVATE | Win32.FlagsSetWindowPos.SWP_NOMOVE | Win32.FlagsSetWindowPos.SWP_NOSIZE | Win32.FlagsSetWindowPos.SWP_NOZORDER | Win32.FlagsSetWindowPos.SWP_NOOWNERZORDER | Win32.FlagsSetWindowPos.SWP_FRAMECHANGED); }