void __fastcall TForm1::Button1Click(TObject *Sender)
{
    TCanvas *btncan = new TCanvas();
    btncan->Handle = GetDC(Button1->Handle);
    btncan->Brush->Color = clBlue;
    btncan->Brush->Style = bsBDiagonal;
    btncan->Pen->Color = clWhite;
    btncan->Rectangle(Button1->ClientRect);
    ReleaseDC(Button1->Handle, btncan->Handle);
    delete btncan;
}