In Windows 3.1, display drivers can use icons larger than 64-by-64 bits and cursors larger than 32-by-32 bits. Large icons and cursors can improve screen readability for high-resolution graphics adapters.
Display drivers specify icon and cursor size in the IconXRatio, IconYRatio, CurXRatio, and CurYRatio members of the CONFIG.BIN resource (that is, the resource having identifier 1 and type OEMBIN). In Windows 3.1, these members specify either a width and height in pixels, or a compression ratio. In Windows 3.0, these members only specify compression ratios. For more information about the members, see the Microsoft Windows Device Driver Adaptation Guide.
In all cases, each icon or cursor must have the same width and height (measured in pixels).
Display drivers which specify actual widths and heights in the OEMBIN resource cannot be used with Windows 3.0. Drivers which specify compression factors work with both Windows 3.0 and 3.1. However, drivers cannot simultaneously specify compression factors with icons or cursors larger than 32-by-32 bits.