Log Message:
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wxMSW: Repaint all windows upon system color change
The problem is when the system switches between dark and light mode,
Refresh() is never called. More specifically, when WM_SETTINGCHANGE
occurs with "ImmersiveColorSet", HandleSettingChange() is not called.
But that is where the only Refresh() call is.
Top level windows should get Refresh() upon WM_SYSCOLORCHANGE as well as
WM_SETTINGCHANGE. Adding another Refresh() call into
HandleSysColorChange() solves the problem.