[news.eclipse.platform.swt] coolbar limit to 1 line?

["outlook express 6" <outlook@xxxxxxxxxxxxx>]

I have a coolbar, in a gridlayout

I have 5 coolItems.  I do not want this coolbar to ever be more than 1 line.

How do I limit it to 1 line?

It initially displays properly all on one line, but I can still drag a second
coolitem down to a lower line,  which conceals what is normally below it.