For a density map in RGB mode, each dataset is assigned a colour channel to which it contributes. A representation of this is displayed in a button to the right of its name in the dataset selector panel at the bottom of the density map window. If you click this button the following dialogue will pop up which enables you to change the colour channel.
Style editor dialogue for density map
The Legend box defines how the selected set will
be identified in the legend which appears alongside the plot
(though the legend will only be visible if Show Legend
() is on):
The Channel selector allows you to select either the Red, Green or Blue channel for this dataset to contribute to. Note that this is only enabled in RGB mode; in indexed mode it has no effect and is disabled.