By using the colour mixing panel, the user can specify the first colour and the last colour for a customized colour bar.
After the selection of the two endpoint colours, pressing the ``Interpolate'' push button will do a linear interpolation of colours from the first colour to the last colour. The result of the interpolation is displayed in the colour bar.
The two markers on the colour bar may be moved left or right, and then pressing the ``Interpolate'' push button again will change the contents of the colour bar such that the colours within the colour bar are linearly interpolated between these end points.