При повороте змейки видно меню

Uses crt, graphABC, events,timers;
type
TDirection = (None, Left, Right, Up, Down);
const
r=15 ;
B=20;
d=8;
 
Var
    i, a: integer;
    s: string[63];
    k: char;
    x,t,y,z,xr,yr,prin1,prin2,prin3,prin4,prin5,g,s4et,prin6: integer;
 Direction :TDirection;
 xs,ys,bufx,bufy:array[1..200]of integer;
 
Procedure BuildMenu;
 
Const
    l: array[1..5] of string[5] = (
    'Easy','Medium','Hard', 'About', 'Exit');
Begin
ClrScr;
//cursoroff;
For i := 1 to 5 do
begin
    If i = a then
      TextColor(Red)
    Else TextColor(Black);
    gotoxy(44,10+i);
      WriteLn(l[i]);
end;
End;
 
procedure shar3;
 begin
 SetBrushColor(clYellow);
 circle(xs[g],ys[g],r);
 end;
 
procedure Circl;
begin
 SetBrushColor(clred);
 circle(x,y,B);
end;
 
procedure rshar ;
 begin
 xr:=Random(WindowWidth) ;
 yr:=Random( WindowHeight);
 end;
 
procedure rshar2;
 begin
 SetBrushColor(clgreen);
 circle(xr,yr,r);
 end;
 
 procedure XP(Key:integer);
 begin
 case Key of
 VK_Left: Direction := Left ;
 VK_Right:Direction := Right ;
 VK_UP: Direction := UP ;
 VK_Down: Direction :=Down ;
 end;
 circle(x,y,r);
 end;
 
procedure pause;
 begin
 SetWindowSize(640,480);
 for i:=1 to 1 do
 begin
 Circl;
 rshar2;
 ClearWindow;
 rshar2 ;
 prin1:=(xr-x+r)*(xr-x+r)+(yr-y)*(yr-y) ;
 prin2:=(xr-x-r)*(xr-x-r)+(yr-y)*(yr-y) ;
 prin3:=(xr-x)*(xr-x)+(yr-y+r)*(yr-y+r) ;
 prin4:=(xr-x)*(xr-x)+(yr-y-r)*(yr-y-r) ;
 prin5:=R*R;
 if (prin1)<=(prin5) then begin
 rshar ;
 s4et:=s4et+1;
 end;
 
if (prin2)<=(prin5) then begin
 rshar ;
 s4et:=s4et+1;
 end;
 if (prin3)<=(prin5) then begin
 rshar ;
 s4et:=s4et+1;
 end;
 if (prin4)<=(prin5) then begin
 rshar ;
 s4et:=s4et+1;
 end;
 
 case Direction of
 Left: begin x:=x-d; if x<=0 then x:=WindowWidth end;
 Up: begin y:=y-d; if y<=0 then y:=WindowHeight end;
 Right: begin x:=x+d; if x>=WindowWidth then x:=0 end;
 Down: begin y:=y+d; if y>=WindowHeight then y:=0 end;
 end;
 xs[1]:=x;
 ys[1]:=y;
 for g:=1 to s4et do
 begin
 bufx[g]:=xs[g];
 bufy[g]:=ys[g];
 
 end;
 for g:=1 to s4et do
 begin
 xs[g+1]:=bufx[g];
 ys[g+1]:=bufy[g] ;
 end;
 for g:=2 to s4et do
 shar3;
 Circl;
 end;
 end;
Procedure Easy;
begin
rshar;
s4et:=2;
 
 Direction := None;
 
 x:=WindowWidth div 2;
 y:=WindowHeight div 2;
 OnKeyDown:=XP;
 t:=CreateTimer(70, pause);
 end;
 Procedure  Medium;
begin
rshar;
s4et:=2;
 
 Direction := None;
 
 x:=WindowWidth div 2;
 y:=WindowHeight div 2;
 OnKeyDown:=XP;
 t:=CreateTimer(50, pause);
 end;
 Procedure Hard;
begin
rshar;
s4et:=2;
 
 Direction := None;
 
 x:=WindowWidth div 2;
 y:=WindowHeight div 2;
 OnKeyDown:=XP;
 t:=CreateTimer(25, pause);
 end;
Procedure About;
Begin
  clrscr;
  Textcolor(Red);
  Gotoxy(18,4);
Write(' Óðàëüñêèé ôåäåðàëüíûé óíèâåðñèòåò èì. Á.Í. Åëüöèíà');
Gotoxy(20,5);
Write('Êàôåäðà Âîäîñíàáæåíèÿ è Âîäîîòâåäåíèÿ');
Gotoxy(12,16);
Write('Êóðñîâàÿ ðàáîòà');
Gotoxy(12,17);
Write('Ïî èíôîðìàòèêå');
Gotoxy(12,18);
Write('15-ãðàííèê');
Gotoxy(12,19);
Write('Ãðóïïà: CÒ-140013');
Gotoxy(12,20);
Write('Ñòóäåíò: Ãóáà Íàòàëèÿ "Êàêàÿ-òî"-âíà (äîïèøè ñâî¸ îò÷åñòâî)');
Gotoxy(30,25);
Write('ã.Åêàòåðèíáóðã 2015 ã.');
Readln;
  writeln('Press <SPACE> to quit.');
  while true do
   begin
     k:=readkey;
     if k=#32 then
       exit;
   end;
End;
{------------------------------------------------}
 
Begin
  SetWindowWidth(768);
  SetWindowHeight(576);
 
a := 1;
BuildMenu;
 
Repeat
    k := ReadKey;
    If k = #0 then begin
        k := ReadKey;
        Case k of
            #72: begin
                a := a - 1;
                If a < 1 then a := 5;
            end;
            #80: begin
                a := a + 1;
                If a > 5 then a := 1;
            end;
        end;
    end
    Else
    begin
        If k = #13 then
        Case a of
            1: Easy;
            2: Medium;
            3: Hard;
            4: About;
            5: Exit;
        end;
    end;
    BuildMenu;
 
Until k = #27;
End.