void __fastcall TForm1::Button1Click(TObject *Sender)
{
// Panel1 ist das Panel was eingefärbt werden soll
HDC hdc = GetDC(Panel1->Handle);
TCanvas* canvas = new TCanvas;
canvas->Handle = hdc;
canvas->Pen->Color = clRed;
canvas->PenPos = Point(0, Panel1->Height - 2);
canvas->LineTo(Panel1->Width - 2, Panel1->Height - 2);
canvas->LineTo(Panel1->Width - 2, 0);
canvas->PenPos = Point(Panel1->Width - 1, 0);
canvas->LineTo(Panel1->Width - 1, Panel1->Height - 1);
canvas->LineTo(0, Panel1->Height - 1);
delete canvas;
ReleaseDC(Panel1->Handle, hdc);
}