Program: 121134
Project: 121134
Buggy source:
@Override public void setActivePage(final IEditorPart activeEditor){
  if ((activeEditorPart == activeEditor) || (activeEditor == null)) {
    return;
  }
  activeEditorPart=activeEditor;
  IActionBars actionBars=getActionBars();
  if (actionBars != null) {
    actionBars.setGlobalActionHandler(ActionFactory.DELETE.getId(),getAction(activeEditor,ActionFactory.DELETE.getId()));
    actionBars.setGlobalActionHandler(ActionFactory.UNDO.getId(),getAction(activeEditor,ActionFactory.UNDO.getId()));
    actionBars.setGlobalActionHandler(ActionFactory.REDO.getId(),getAction(activeEditor,ActionFactory.REDO.getId()));
    actionBars.setGlobalActionHandler(ActionFactory.CUT.getId(),getAction(activeEditor,ActionFactory.CUT.getId()));
    actionBars.setGlobalActionHandler(ActionFactory.COPY.getId(),getAction(activeEditor,ActionFactory.COPY.getId()));
    actionBars.setGlobalActionHandler(ActionFactory.PASTE.getId(),getAction(activeEditor,ActionFactory.PASTE.getId()));
    actionBars.setGlobalActionHandler(ActionFactory.SELECT_ALL.getId(),getAction(activeEditor,ActionFactory.SELECT_ALL.getId()));
    actionBars.setGlobalActionHandler(ToggleSubjobsAction.ID,getAction(activeEditor,ToggleSubjobsAction.ID));
    activateActionsInViewMenu(activeEditor,actionBars,VIEW_MENU_ACTIONS_ID);
    if (showAndRunProcessAction != null) {
      actionBars.setGlobalActionHandler(showAndRunProcessAction.getActionDefinitionId(),showAndRunProcessAction);
    }
    actionBars.updateActionBars();
  }
}

Fixed version (ground truth):
@Override public void setActivePage(final IEditorPart activeEditor){
  if ((activeEditorPart == activeEditor) || (activeEditor == null)) {
    return;
  }
  activeEditorPart=activeEditor;
  if (activeEditor instanceof TalendEditor) {
    RootEditPart editPart=((TalendEditor)activeEditor).getViewer().getRootEditPart();
    if (editPart != null && editPart instanceof TalendScalableFreeformRootEditPart) {
      ZoomManager manager=((TalendScalableFreeformRootEditPart)((TalendEditor)activeEditor).getViewer().getRootEditPart()).getZoomManager();
      item.setZoomManager(manager);
    }
  }
 else {
    item.setZoomManager(null);
  }
  IActionBars actionBars=getActionBars();
  if (actionBars != null) {
    actionBars.setGlobalActionHandler(ActionFactory.DELETE.getId(),getAction(activeEditor,ActionFactory.DELETE.getId()));
    actionBars.setGlobalActionHandler(ActionFactory.UNDO.getId(),getAction(activeEditor,ActionFactory.UNDO.getId()));
    actionBars.setGlobalActionHandler(ActionFactory.REDO.getId(),getAction(activeEditor,ActionFactory.REDO.getId()));
    actionBars.setGlobalActionHandler(ActionFactory.CUT.getId(),getAction(activeEditor,ActionFactory.CUT.getId()));
    actionBars.setGlobalActionHandler(ActionFactory.COPY.getId(),getAction(activeEditor,ActionFactory.COPY.getId()));
    actionBars.setGlobalActionHandler(ActionFactory.PASTE.getId(),getAction(activeEditor,ActionFactory.PASTE.getId()));
    actionBars.setGlobalActionHandler(ActionFactory.SELECT_ALL.getId(),getAction(activeEditor,ActionFactory.SELECT_ALL.getId()));
    actionBars.setGlobalActionHandler(ToggleSubjobsAction.ID,getAction(activeEditor,ToggleSubjobsAction.ID));
    activateActionsInViewMenu(activeEditor,actionBars,VIEW_MENU_ACTIONS_ID);
    if (showAndRunProcessAction != null) {
      actionBars.setGlobalActionHandler(showAndRunProcessAction.getActionDefinitionId(),showAndRunProcessAction);
    }
    actionBars.updateActionBars();
  }
}