VTermAttrMask
int vterm_screen_get_attrs_extent(const VTermScreen *screen, VTermRect *extent, VTermPos pos, VTermAttrMask attrs);
static int attrs_differ(VTermAttrMask attrs, ScreenCell *a, ScreenCell *b)
int vterm_screen_get_attrs_extent(const VTermScreen *screen, VTermRect *extent, VTermPos pos, VTermAttrMask attrs)