Man pages matching name tickit_pen_set_colour_attr_rgb8 in section 3:

tickit_pen_set_colour_attr_rgb8.3.en	debian 10 / libtickit-dev
tickit_pen_set_colour_attr_rgb8.3.en	debian 11 / libtickit-dev
tickit_pen_set_colour_attr_rgb8.3.en	debian 12 / libtickit-dev