Fui atualizando ou migrando nosso software do sistema operacional XP para poder compilar e executar no Windows 7. Nosso software está começando a mostrar problemas que não notamos no Windows XP. Atualmente, estou lidando com um controle definido pelo usuário que oscila em um TForm. Parece piscar de vez em quando nem sempre, mas quando pisca é muito perceptível. Eu configurei DoubleBuffered para a classe TForm e TTrendChart, mas não está ajudando.

Este é um controle definido pelo usuário do TCustomPanel. Ele deve exibir um gráfico de tendências ao vivo em um TFor

TTrendChart = class(TCustomPanel)
private
  fCount:integer;
  fColors:array[0..7] of TColor;
  fNames:array[0..7] of string;
  fMinText:string16;
  fMaxText:string16;
  fShowNames:Boolean;
  fMaxTextWidth:integer;
  data:TList;
  Indexer:integer;
  chartRect:TRect;
  fWidth:integer;
  fHeight:integer;
  firstTime:Boolean;
  function GetColors(Index:integer):TColor;
  procedure SetColors(Index:integer; const value :TColor);
  function GetNames(Index:integer):string;
  procedure SetNames(Index:integer; const value: string);
  procedure SetCount(const value : integer);
  procedure rShowNames(const value : Boolean);
  procedure SetMaxText(const value:string16);
  procedure SetMinText(const value:string16);
  procedure RecalcChartRect;
protected
  procedure Resize; override;
  procedure Paint; override;
public
  constructor Create(AOwner : TComponent); override;
  destructor Destroy; override;
  procedure PlotPoints(p1,p2,p3,p4,p5,p6,p7,p8:real);
  procedure ClearChart;
  procedure Print;
  property TrendColors[Index:integer]: TColor read GetColors write SetColors;
  property TrendNames[index:integer]: string read GetNames write SetNames;
published
  property TrendCount: Integer read fCount write SetCount default 8;
  property ShowNames: Boolean read fShowNames write rShowNames default true;
  property MaxText:string16 read fMaxText write SetMaxText;
  property MinText:string16 read fMinText write SetMinText;
  property Align;
  property Alignment;
  property BevelInner;
  property BevelOuter;
  property BevelWidth;
  property DragCursor;
  property DragMode;
  property Enabled;
  property Caption;
  property Color;
  property Ctl3D;
  property Font;
  property Locked;
  property ParentColor;
  property ParentCtl3D;
  property ParentFont;
  property ParentShowHint;
  property PopupMenu;
  property ShowHint;
  property TabOrder;
  property TabStop;
  property Visible;

  property OnClick;
  property OnDblClick;
  property OnDragDrop;
  property OnDragOver;
  property OnEndDrag;
  property OnEnter;
  property OnExit;
  property OnMouseDown;
  property OnMouseUp;
  property OnMouseMove;
  property OnResize;
end;

Aqui como ele foi criado:

    constructor TTrendChart.Create(AOwner:TComponent);
var
  i:integer;
  tp:TTrendPoints;
begin
  inherited Create(AOwner);
  Parent := TWinControl(AOwner);
  fCount := 8;
  fShowNames := true;
  Caption := '';
  fMaxText := '100';
  fMinText := '0';
  fMaxTextWidth := Canvas.TextWidth('Bar 0');
  firstTime := true;
  BevelInner := bvLowered;
  data := TList.Create;
  Indexer := 0;
  RecalcChartRect;
  DoubleBuffered:=true;
  for i := 0 to 10 do
  begin
    tp := TTrendPoints.Create(0.0 + 0.1 * fWidth,0.0,0.0,0.0,0.0,0.0,0.0,0.0);
    data.Add(tp);
  end;
  for i := 0 to 7 do
  begin
    case i of
    0: fColors[i] := clMaroon;
    1: fColors[i] := clGreen;
    2: fColors[i] := clOlive;
    3: fColors[i] := clNavy;
    4: fColors[i] := clPurple;
    5: fColors[i] := clFuchsia;
    6: fColors[i] := clLime;
    7: fColors[i] := clBlue;
    end;
    fNames[i] := Format('Line %d',[i]);
  end;

end;

Aqui está como é pintado no Formulário:

    procedure TTrendChart.Paint;
var
  oldColor:TColor;
  dataPt:TTrendPoints;
  i,j:integer;
  curx:integer;
  count,step:integer;
  r:TRect;
begin
   inherited Paint;

  oldcolor := Canvas.Pen.Color;

  Canvas.Brush.Color:=clWhite;
  r.Left:=chartRect.Left-25;
  r.Right:=chartRect.Right+11;
  r.Top:=chartRect.Top-11;
  r.Bottom:=chartRect.Bottom+22;
  Canvas.FillRect(r);

  if FirstTime then
  begin
    count := Indexer - 1;
  end
  else
    count := data.Count - 2;

    { Draw minute lines }
    Canvas.Pen.Color := clBtnShadow;
    i := chartRect.left + 60;
    while i < chartRect.Right do
    begin
         Canvas.Moveto(i, chartRect.top);
         Canvas.LineTo(i, chartRect.bottom);
         i := i + 60;
    end;

    { Draw value lines }

    step := (chartRect.bottom - chartRect.top) div 5;

    if step > 0 then
    begin
         i := chartRect.bottom - step;
         while i > (chartRect.top + step - 1) do
         begin
              Canvas.Moveto(chartRect.left,i);
              Canvas.LineTo(chartRect.right,i);
              i := i - step;
         end;
    end;

  { Draw Pens }
  for j := 0 to fCount - 1 do
  begin
    Canvas.Pen.Color := fColors[j];
    dataPt := TTrendPoints(data.Items[0]);
    Canvas.MoveTo(chartRect.left,PinValue(round(chartRect.bottom - (fHeight * dataPt.pnts[j] / 100.0)),
                                                                 chartRect.top,chartRect.bottom));

    for i := 1 to count do
    begin
      dataPt := TTrendPoints(data.Items[i]);
      if i <> Indexer then
      begin
           Canvas.LineTo(chartRect.left+i,PinValue(round(chartRect.bottom - (fHeight * dataPt.pnts[j] / 100.0)),
                                                               chartRect.top,chartRect.bottom));
      end
      else
      begin
           Canvas.MoveTo(chartRect.left+i,PinValue(round(chartRect.bottom - (fHeight * dataPt.pnts[j] / 100.0)),
                                                                 chartRect.top,chartRect.bottom));
      end;
    end;
  end;

    r := chartRect;
    InflateRect(r,1,1);
    Canvas.Pen.Color := clBtnShadow;
    Canvas.moveto(r.left,r.top);
    Canvas.lineto(r.right,r.top);
    Canvas.lineto(r.right,r.bottom);
    Canvas.lineto(r.left,r.bottom);
    Canvas.lineto(r.left,r.top);

    { draw index line }
//    Canvas.Pen.Color := clWhite;
    Canvas.Pen.Color := clBlack;    
    Canvas.MoveTo(chartRect.Left + Indexer,chartRect.top);
    Canvas.LineTo(chartRect.left + Indexer, chartRect.bottom+1);
    Canvas.Pen.Color := oldcolor;

    Canvas.Font.COlor := clBlack;
    Canvas.TextOut(chartRect.left-Canvas.TextWidth(string(fMinText))-2,chartRect.Bottom-8,string(fMinText));
    Canvas.TextOut(chartRect.left-Canvas.TextWIdth(string(fMaxText))-2,chartRect.top-8,string(fMaxText));

    if fShowNames then
    begin
      curx := 32;
      for i := 0 to fCount - 1 do
      begin
        Canvas.Font.Color := fColors[i];
        Canvas.TextOut(curx,chartRect.bottom+4,fNames[i]);
        curx := curx +  fMaxTextWidth + 16;
      end;
    end;
end;

Aqui está como se usaria:

  TrendChart := TTrendChart.Create(form);

Qualquer ajuda será apreciada. Obrigado