void push_arrangement(Arrangement &);
Arrangement *get_arrangement() const;
void pop_arrangement(Arrangement &);
void push_arrangement(Arrangement &);
Arrangement *get_arrangement() const;
void pop_arrangement(Arrangement &);
/// Sets a widget as a ghost, taking up space even if it is hidden.
void set_ghost(Widget &, bool);
/// Sets a widget as a ghost, taking up space even if it is hidden.
void set_ghost(Widget &, bool);