I would like to define a PANEL window outside of the initial declaration (as in a PANEL array). I tried the following:

PANEL hp_bar[5];

(hp_bar[0]).window = (20, 20, 20, 5, healthbar, (spr[0].cur_hp/spr[0].max_hp)*600, 0);

However, apparently window is not a member of PANEL.

Any help would be appreciated.
Thanks in advance.