title: Custom button inherited from TButton does not show
body: <p>I am converting a large project to Firemonkey and we have some custom buttons, which does not show on the form. I have isolated the problem to a very simple project: </p>
  
  <p>With the code below, on both mobile and desktop (using default new applications in Delphi XE6), creating tTestButton1 works fine, but tTestButton2 does not show on the form. How is that possible?</p>
  
  <pre><code>type
  tTestButton1 = class(TButton);
  tTestButton2 = class(tTestButton1);
  
  tMainForm = class(TForm)
  private
    fTestButton: TButton;
  public
    constructor Create(aOwner: TComponent); override;
  end;
  
  constructor tMainForm .Create(aOwner: TComponent);
  begin
    inherited;
  
  //  fTestButton := tTestButton1.Create(Self); // this works fine (used instead of next line)
    fTestButton := tTestButton2.Create(Self);  //this button does not show up
    fTestButton.Text := 'Test';
    fTestButton.Parent := Self;
    fTestButton.Visible := True;
    fTestButton.Position.X := 20;
    fTestButton.Position.Y := 20;
  end;
  </code></pre>