ee2b02614e
It can be used to scale coordinates and sizes to make them DPI aware.
In the common headers, use wxDisplay::GetStdPPIValue() as default DPI value,
so the correct values are used on Windows (96) and macOS (72).
In wxMemoryDC use m_contentScaleFactor as the DPIScaleFactor, see e4c2298e5e
(Use window scale factor for all MSW wxDCs associated with windows, 2022-04-04).