A JInternalFrame can be sized off of the desktop in which it resides. This is a
problem because the title bar of the JInternalFrame can disappear off the top of
the desktop, and there is no way to resize the window or bring it back onto the
desktop.

In the attached sample program, grab the top border (not the title bar) of the
JInternalFrame and then pull it way up (higher than the top of the external frame), and then mouse up. The JInternalFrame is "stuck" with the title off of
the desktop. (Same behavior for Windows or Metal look and feel.)