Working Version: Painted Bars/BarDimming
//@version=4 study("PaintedBars/BarDimming", overlay=true)
bar_color = bar_index < (bar_index[max(0, barstate.isrealtime ? bar_index - 1 : 0)] - 25) ? color.green : color.red
barcolor(color.green, -25)
Try :
barcolor(color.green, -25)