BottomBar does not center and resize properly

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What steps will reproduce the problem?
1. Add a wide left component, a center component, and a narrow right component 
to BottomBar
2. Play around with resizing the window

What is the expected output? What do you see instead?
I expect (and do not see):
1. The center component should be visually centered within the width of the 
window to the extent possible
2. All whitespace should be consumed before truncating the right component off 
the edge of the window

What version of the product are you using? On what operating system?
trunk r377 on OSX 10.6.4

Please provide any additional information below.
When I comment the following line in the BottomBar constructor it seems to be 
much better behaved:

fBottomBar.forceAreasToHaveTheSameWidth();

Maybe we could get rid of this call, or at least provide a different 
constructor or setter to control this behavior?

Original issue reported on code.google.com by garrick....@gmail.com on 17 Nov 2010 at 7:39