afx_msg void OnSysColorChange();
Called for all top-level windows when a change is made in the system color setting.
Windows calls OnSysColorChange for any window that is affected by a system color change.
Applications that have brushes that use the existing system colors should delete those brushes and re-create them by using the new system colors.
This message-handler member function calls the Default member function. Override this member function in your derived class to handle the WM_SYSCOLORCHANGE message.
::SetSysColors, WM_PAINT, CWnd::Default, WM_SYSCOLORCHANGE