how to colorize the entire line of selected messages ?

[Virginie \[ ML \]]

Hi,
Does anybody know how I could color the entire line of selected messages in front of 
the indicator ?
I've set :
indicator brightcyan black
But as you know it just colors the arrow and I didn't find any other options :(
And I'm not sure at all that it must be defined in the indicator's
colors..

Any idea?