Incomplete legend info for parameterised layers

[GoogleCodeExporter]

What steps will reproduce the problem?
1. Add a parameterised layer (like ncWMS or a layer with time support)
2. Change a parameter (like the time)
3. The legend do not give any information about the parameter value

What is the expected output? What do you see instead?
Something in the legend that tells what is the value of the parameter, like the 
date of the layer for time based layers.

What version of the product are you using? On what operating system?
1.4.5 (that bug has been there for ever)

Please provide any additional information below.
This bug is particularly annoying when doing a printed map. It makes the legend 
pretty much useless for those layers.

Original issue reported on code.google.com by lafond.g...@gmail.com on 1 Aug 2013 at 11:56