scr_screen = DefaultScreen (dd);
scr_depth = DefaultDepth (dd, scr_screen);
scr_height = DisplayHeight (dd, scr_screen);
scr_width = DisplayWidth (dd, scr_screen);
root_win = RootWindow (dd, scr_screen);
Only the position is needed.
see fspanel.c, here the code of fspanel.c :
https://termbin.com/0yss