Contacts button in the main toolbar?

Is there a way to add a Contacts button to the main toolbar? Couldn’t fine anything in the help or in these forums. I would rather have a button in the toolbar than in the left panel. A button that pops up a small window like ctrl-b does would be great. Thanks.

Not possible because it is not a main toolbar, but actually the message preview toolbar and only has items that apply to messages.

In version 8, the section buttons have been redesigned but are still in the lower left of the screen.

Version 7:

Version 8: