9:31:46splittistThere is a call in MAYBE-ADD-AUXILIARY-PANES to (PORT frame), when trying to MAKE-INSTANCE the 'VRACK-PANE for the menu bar. But MAYBE-ADD-AUXILIARY-PANES is called within GENERATE-PANES :AFTER before the FRAME is adopted by the TOP-LEVEL-SHEET. Because (?) A-WINDOW-STREAM is a STANDARD-EXTENDED-INPUT-STREAM before it is a STANDARD-APPLICATION-FRAME, the PORT accessor method on STANDARD-SHEET-INPUT-MIXIN is called rather than the
9:31:46splittistPORT method on STANDARD-APPLICATION-FRAME, returning NIL rather than the PORT of the FRAME-MANAGER (which the latter method would give).
9:32:15splittistSo MAKE-MEDIUM is called with NIL as port when trying to create the VRACK-PANE.