当“标题栏”设置为不显示时，为什么我无法在NSPanel中获得焦点？

If I create a project in Xcode 4.1, and set the MainMenu.xib to have two NSPanels, and put a NSTextField in both panels, if I set one of the NSPanels to not show the "Title Bar", then the textfield within that panel can not be clicked on or given focus. If I create a project in Xcode 4.1, and set the