OptionalbackgroundOptionalbackgroundthe track's own art; a plain colour rect (the theme's panel fill) when omitted
Optionalcolorthe filled colour; defaults to the theme's highlight colour. Tints fillTexture too, when both are given
Optionalfillthe fill's own art, stretched to the filled width; a plain colour rect (the default) when omitted
OptionalmaxOptionalroundRounds the filled width up to the next whole pixel instead of a fractional one, so a sliver of value (1 hp of 300, say) never rounds down to nothing. Off by default, since it very slightly overstates the fraction at low values - a game where that sliver matters more than the precision opts in.
Optionalvaluestarting value, read the same way setValue is; defaults to full
The track's own colour; the theme's panel fill when omitted. Ignored when
backgroundTextureis given, which owns the track's appearance instead.