Unfortunately, the box function does not have a transparency attribute to enable the candle to show through. You could use the bgcolor function to highlight the candle you want which you can specify a transparency for, however, it will be a vertical line with no control over height or placement.
Actually , the box function does have a transparency attribute as I am using it atm to fade the box color. But this is not really what i am trying to do. After further research , I think it is the z index I need to change in order to plot the box behind the candles rather then on top. However , z does not seem to be available in pinescript.Thank you anyway Steve .... R .
I just looked up all the box attributes and again couldn't find transparency in the language reference. Just out of interest, how are you using it or do I just have blinkers on lol?