These functions are exactly like the corresponding libdialog functions, for the unsurprising reason that they need to do much the same as they would in libdialog.
=init_dialog()=
    init_dialog()
    initialize the dialog library; start curses, allocate colors,
    clear the screen, allocate the helpline, and so on.
After `init_dialog()`, the screen will be cleared, set to the window
color, and (invisibly) broken up into the form window and a one-line
helpline window at the bottom of the screen.
=end_dialog()=
    end_dialog()
    Close up shop and shut curses down.
=use_helpline()=
    `use_helpline(message)
    Set the helpline to the given message.
=get_helpline()=
    get_helpline()
    Return a pointer to the existing helpline.
=restore_helpline()=
    restore_helpline(message)
    I’m not sure what this is supposed to do;  it’s aliased to use_helpline()
    right now.
=strwidth()=
    strwidth(message)
    Return how many columns wide a message is.
=strdepth(), strheight()=
    strdepth(message)
    strheight(message)
    Return how many rows deep a message is.