You can draw individual pixels with the two methods Gdk::Drawable::draw_point() and 
      Gdk::Drawable::draw_points(). All drawing methods take a Gdk::GC as their first
      argument, except where noted. The other two arguments to draw_point() are the x coordinate
      (horizontal position relative to the left edge of the widget, starting at 0), and the y coordinate (vertical position
      relative to the top of the widget, starting at 0). draw_points() takes two arguments, the
      Gdk::GC and a collection of Gdk::Points. The second argument can be any kind
      of standard container, such as a std::vector<Gdk::Point>. So for example
      draw_point() could be used like this:
    
get_window()->draw_point(some_gc, 20, 20);
      But draw_points() is a bit more complicated and might be used like this:
    
std::vector<Gdk::Point> points_array;
points_array.push_back(Gdk::Point(10, 10));
points_array.push_back(Gdk::Point(20, 20));
draw_points(some_gc, points_array); //One way to draw the two points.