The DRAW_COLOR_HISTOGRAM drawing style is used to plot color histograms.
The indicator plots a sin(x) function as a color histogram in a separate window. Two indicator buffers are used: the first contains the values of sin(x) function, the color indexes specified in the second indicator buffer. The histogram colors, the width and line style changed randomly after N=5 ticks. The initial properties of the plot1 graphic plot are defined using the #property preprocessor directive, further these properties changed randomly (see OnCalculate() function).
See also The Drawing Styles in MQL5.