Delphi 2009 - create a TPanel at runtime and change its color

When you want to have colored panels under a themed OS you have to set ParentBackground to False.

Try this :-)

procedure TForm1.Button1Click(Sender: TObject);
var
  pnlTest : TPanel;
begin
    pnlTest := TPanel.Create(Form1);
    pnlTest.Parent := Form1;
    pnlTest.Width := 100;
    pnlTest.Height := 100;
    pnlTest.ParentBackground := false;
    pnlTest.Color := clRed;
end;