/// this stores metrics information in cache_
void metrics(MetricsInfo & mi, Dimension & dim) const;
/// draw according to cached metrics
void draw(PainterInfo &, int x, int y) const;
/// draw selection background
/// this stores metrics information in cache_
void metrics(MetricsInfo & mi, Dimension & dim) const;
/// draw according to cached metrics
void draw(PainterInfo &, int x, int y) const;
/// draw selection background