It was CTRL + tab in the Pharo 1.4
This hack was to override Morph>>tabKey: event�
in that execute a new method block [ World tabOpenWindows: event ].
PasteUpMorph>>
tabOpenWindows: aKeyboardEvent
| currentFocus index |
currentFocus := aKeyboardEvent hand keyboardFocus.
SystemWindow noteTopeWindowIn: self.
System topWindow sendToBack.
this did work well in 1.4 but in 2.0 there is an override to key handling with KMDispatcher >> dispatchKeystroke: aKeyEvent that not so clearly ends up handling CTRL+tab�
Need to check and revert if that hack can be plugged on to 2.0 trivially.