The 'minimize' 'maximize' and 'close' buttons of a JInternalFrame's frame
decoration should be exposed as accessible objects.

This can be reproduced in the SwingSet2 demo, using at-poke:-

Switch to the 'Internal Frames Demo' in SwingSet2.
Expand the widget tree in at-poke for one of the JInternalFrames.

You will be unable to find an object representation for any of
'minimize' 'maximize' or 'close'.