procedure TForm1.ComboBox1DrawItem(Control: TWinControl; Index: Integer;
Rect: TRect; State: TOwnerDrawState);
var
strVal, strAll: string;
pos1, pos2: Integer;
rc: TRect;
arrWidth: array [0..3] of Integer;
arrColor: array [0..7] of TColor;
begin
arrColor[0]:= clAqua;
arrColor[1]:= clBlack;
arrColor[2]:= clBlue;
arrColor[3]:= clDkgray;
arrColor[4]:= clfuchsia;
arrColor[5]:= clgreen;
arrColor[6]:= cllime;
arrColor[7]:= clolive;

Combobox1.Canvas.Brush.Style := bsSolid;
Combobox1.Canvas.FillRect(Rect);
strAll := Combobox1.Items[Index];

arrWidth[0] := 0;
arrWidth[1] := 100; // Width of column 1
arrWidth[2] := 200; // Width of column 2
arrWidth[3] := 300; // Width of colimn 3

rc.Left := Rect.Left + arrWidth[0] + 2;
rc.Right := Rect.Left + arrWidth[1] - 2;
rc.Top := Rect.Top;
rc.Bottom := Rect.Bottom;

pos1 := Pos(';', strAll);
strVal := Copy(strAll, 1, pos1 - 1);
Combobox1.Canvas.Brush.Color := arrColor[index];
Combobox1.Canvas.TextRect(rc, rc.Left, rc.Top, strVal);
Combobox1.Canvas.MoveTo(rc.Right, rc.Top);
Combobox1.Canvas.LineTo(rc.Right, rc.Bottom);


rc.Left := Rect.Left + arrWidth[1] + 2;
rc.Right := Rect.Left + arrWidth[2] - 2;
strAll := Copy(strAll, pos1 + 1, Length(strAll) - pos1);
pos1 := Pos(';', strAll);
strVal := Copy(strAll, 1, pos1 - 1);

Combobox1.Canvas.Brush.Color := arrColor[index+1];
Combobox1.Canvas.TextRect(rc, rc.Left, rc.Top, strVal);
Combobox1.Canvas.MoveTo(rc.Right, rc.Top);
Combobox1.Canvas.LineTo(rc.Right, rc.Bottom);

rc.Left := Rect.Left + arrWidth[2] + 2;
rc.Right := Rect.Left + arrWidth[3] - 2;
strAll := Copy(strAll, pos1 + 1, Length(strAll) - pos1);
pos1 := Pos(';', strAll);
strVal := Copy(strAll, 1, pos1 - 1);
Combobox1.Canvas.Brush.Color := arrColor[index+3];
Combobox1.Canvas.TextRect(rc, rc.Left, rc.Top, strVal);
Combobox1.Canvas.MoveTo(rc.Right, rc.Top);
Combobox1.Canvas.LineTo(rc.Right, rc.Bottom);
strAll := Copy(strAll, pos1 + 1, Length(strAll) - pos1);
end;

procedure TForm1.Button1Click(Sender: TObject);
var i:integer;
begin
for i:=1 to 10 do
with Combobox1.Items do
begin
Add(inttostr(i)+'.Satır;second;third;');
end;
end;