Section Header
    + name := G_BUTTON;
    - author := "Sonntag Benoit (bsonntag@loria.fr)";
    - comment := "Group elements for GUI.";
Section Inherit
    + parent_g_group:Expanded G_GROUP;
Section Public
    + auto_action:G_WIN_OUT;
    + stat:INTEGER_8;
    + action:BLOCK :=
Creation
    - create elt:G_EXPR connect a:G_WIN_OUT :SELF <-
    - make elt:G_EXPR connect a:G_WIN_OUT <-
    - create elt:G_EXPR action b:BLOCK :SELF <-
    - make elt:G_EXPR action b:BLOCK <-
Size.
    - width_min:INTEGER <-
    - height_min:INTEGER <-
Update position.
    - set_position rac:AREA at (x,y:INTEGER) size (w,h:INTEGER) <-
Display.
    - draw_slave bmp:ABSTRACT_BITMAP from (x0,y0:INTEGER) to (x1,y1:INTEGER) <-
    - draw (x0,y0:INTEGER) to (x1,y1:INTEGER) <-
Event manager.
    - receive msg:EVENT <-
        stat :
        -1 = Not actif
        0 = out & off
        1 = in & off
        2 = out & on
        3 = in & on