let previous_yAction (() : unit) : unit =
let rec aux lock =
if((!yOrd)< ((!ymax)-. !yMarge -. !yDelta))
then(
yOrd := (!yOrd)+.(!yDelta);
if(lock && in_click_zone_y (!yOrd)) then (let old_y = (!yOrd) in aux false ; del_zone_y old_y)
else if(in_zone (!yOrd) ) then ( aux false )
else if not(lock) then yOrd := (!yOrd)-.(!yDelta);
)
in aux true;
Canvas.configure canvas ~scrollregion:((xconv ((-1.) *. 10. -. 5. )) - (5*(get_max_length_message()) ),0,(xconv ((float_of_int(!nbAgents + 1)) *. 10. +. 5. )) + (5*(get_max_length_message())), (yconv !yOrd));