Rehan discovered a bug in Java Swing.  When using tabbed frames, you need to insert an extra pane before embedding any more ingredients into a single tab.  This has been documented:  Link to Forum discussion on this 

But, if you try to set any type of layout on this interior pane, you will experience problems with shrinkage  of the various controls.  They shrink like frightened turtles are unusable and hideous. The controls come back when the window is enlarged by clicking and dragging, and then shrink again when the window is reduced to its original size.  To avoid this, he is getting by without setting any layout.  This could hold someone back, however, if they needed to do a layout on this pane. 

12:18:23 PM    comment []