Hi there,
For a healthbar I would use:

hslider (x, y, len, bmap, min, max, var);

or if you going for a vertical bar:

vslider (x, y, len, bmap, min, max, var);

You can find more informations/examples in the manual.

cheers

EDIT: Nah sorry, window is the better way to go. sliders are more for actuators.