Theme editor: detail about time colour

I have a question to experts on the theme editor:

When I change the following colour…

Forms > Main form > Message list > MessagesMultilineTimeColor

… this setting will change the time colour not only in the message list but also in the right side bar, where I show the agenda.

Is there any way to override this? I would like to have the time black in the message list but white in the agenda in the side bar.