Name of a IUP image.
Icon sizes are usually less than or equal to 32x32. On Windows, names of resources (.RES) linked to the application are also accepted. On Motif, it only works with some window managers, like mwm and gnome. Icon colors can have the BGCOLOR values, but it works better if it is at index 0.
The Windows SDK recomends that cursors and icons should be implemented as resources rather than created at run time.