void draw_main_heading(std::vector<TextDefer> &td);
void draw_column_headings(std::vector<TextDefer> &td, const Group &group, const std::vector<unsigned> &colwidth);
void draw_main_heading(std::vector<TextDefer> &td);
void draw_column_headings(std::vector<TextDefer> &td, const Group &group, const std::vector<unsigned> &colwidth);