Initialize the SLsmg routines
int SLsmg_init_smg (void)
The SLsmg_init_smg function initializes the SLsmg screen
management routines. Specifically, this function allocates space
for the virtual display and calls SLtt_init_video to put the
terminal's physical display in the proper state. It is up to the
caller to make sure that the SLtt routines are initialized via
SLtt_get_terminfo before calling SLsmg_init_smg.
This function should also be called any time the size of the physical display has changed so that it can reallocate a new virtual display to match the physical display.
It returns zero upon success, or -1 upon failure.
SLsmg_reset_smg