WM_SYSCOLORCHANGE
The WM_SYSCOLORCHANGE message is sent to all top-level windows when a change is made in the system color setting.
This message has no parameters.
An application should return zero if it processes this message.
Windows sends a WM_PAINT message to 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.