#include <curses.h>
int bkgrnd( const cchar_t *wch);
int wbkgrnd( WINDOW *win, const cchar_t *wch);
void bkgrndset(const cchar_t *wch );
void wbkgrndset(WINDOW *win, const cchar_t *wch);
int getbkgrnd(cchar_t *wch);
int wgetbkgrnd(WINDOW *win, cchar_t *wch);
To the extent possible on a particular terminal, the attribute part of the background is displayed as the graphic rendition of the character put on the screen.
The bkgrnd and wbkgrnd functions set the background property of the current or specified window and then apply this setting to every character position in that window:
The rendition of every character on the screen is changed to the new background rendition.
Wherever the former background character appears, it is changed to the new background character.
The getbkgrnd function returns the given window's current background character/attribute pair via the wch pointer.
Upon successful completion, the other functions return OK. Otherwise, they return ERR. A null window pointer is treated as an error.