我怎样才能让jtoolbar自动换行到下一行(FlowLayout)，而不让它们隐藏在下面的JPanel中呢?

I am in the process of making a GUI which shows three JToolBars above a big JPanel. These toolbars are collectively very large, so I'm using a FlowLayout to make them wrap to the next line if they reach the JFrame border. The problem is that when they wrap to the next line, they become hidden by the JPanel below.. I wish I could force the JPanel containing the toolbars to grow enough to show all toolbars..I am in the process of making a GUI which shows