The history of which cells have been pushed to and popped from is saved. Assume that previously one has pushed into the hierarchy and popped back. When the Push button is active, pressing the Enter key will push down one level and deactivate the button. Holding the Ctrl key while pressing Enter will suppress the button deactivation, so that one can press Enter repeatedly to push deeper into the hierarchy, following the last push sequence. Pressing Shift-Enter will cycle backwards, i.e., pop, with button deactivation controlled by the Ctrl key as above. Unless the Ctrl key was up during the last context change, the Push command is still active and one must press Esc before the cell can be edited.
If instead of pressing Enter a subcell is clicked on, the subcell is pushed to in the usual way, and all past history below the present level is removed.