截获重画消息：
TForm1 = class(TForm)
private
{ Private declarations }
procedure WMPaint(var Message: TWMPaint); message WM_PAINT;
public
{ Public declarations }
end;
var
Form1: TForm1;
implementation
{$R *.dfm}
procedure TForm1.WMPaint(var Message: TWMPaint);
begin
;
end;
