void endUndoGroup();
/// end the current undo group and set UndoElement::cur_after if necessary.
void endUndoGroup(CursorData const & cur_after);
+ /// end abruptly the current group and create a new one wih the same nesting level
+ void splitUndoGroup(CursorData const & cur);
/// return true if an undo group is open and contains at least one element
bool activeUndoGroup() const;