Today Usman and I have pair-programmed. We improved the legend builder. 
Here is an example

Check this out:
b := RTMondrian new.
b shape rectangle
width: [ :c | c numberOfVariables * 5 ];
height: #numberOfMethods.
b nodes: RTShape withAllSubclasses.
b edges connectFrom: #superclass.
b layout tree.
b normalizer
normalizeColor: #numberOfLinesOfCode using: { Color black. Color red }.
b build.

lb := RTLegendBuilder new.
lb view: b view.

lb addText: 'System complexity view'.
lb addRectanglePolymetricWidth: 'number of methods' height: 'Line of code' box: 'a Pharo class'.

lb addColorFadingFrom: Color red to: Color black text: 'Number of lines of code'.
lb build.


Alexandre Bergel  http://www.bergel.eu