Usually your program will be suspended when it has no access to the screen but see vga_runinbackground(3) for an alternative.
svgalib(7), vgagl(7), libvga.config(5), bg_test(6), vga_runinbackground(3), vga_runinbackground_version(3)
This manual page was edited by Michael Weller <email@example.com>. The exact source of the referenced function as well as of the original documentation is unknown.
It is very likely that both are at least to some extent are due to Harm Hanemaayer <H.Hanemaayer@inter.nl.net>.
Occasionally this might be wrong. I hereby asked to be excused by the original author and will happily accept any additions or corrections to this first version of the svgalib manual.