Wrong color coding for histogram

[alexsb]

Here the color coding is applied based on the hight of the bar. It should, however, be applied based on the position of the histogram bar on the data scale. E.g, if it's from white to red, on the scale of 0 to 10, the bar should be white on the far left and red on the far right, independent of the height of the bar.

Here is an example for a blue-white-red color-scale. Ignore the "sliders" on the left/right for now.