Question How do I inherit a Form?

{ TCommonForm }
 TCommonForm = class(TForm)
  procedure FormCreate(Sender : TObject);
 private

 public

 end;

{ TForm1 }
 TForm1 = class(TCommonForm)
  procedure FormCreate(Sender : TObject);
 private

 public

 end;

procedure TForm1.FormCreate(Sender : TObject);
begin
  inherited;
end;

{$if defined(IS_IDE_WORK)} // do not work!!! I figured it out later and corrected the message.
TForm1 = class(TForm)
{$else}
TForm1 = class(TCommonForm}
{$endif}

(*
 *** KodeZwergs Interceptor Example ***
  copy "Interceptor.pas" into your Path where it's accessible from everywhere.
  must be included as last "Uses" statement in "Interface" section to let it work automagically.
*)

unit Interceptor;

interface

uses
  Forms;

type
  { interceptor class for TForm }
  TForm = class(Forms.TForm)
  protected
  private
  public
    constructor Create(AOwner: TComponent); override;
  public
  end;

implementation

constructor TForm.Create(AOwner: TComponent);
begin
  inherited Create(AOwner);
// add more code here
end;

initialization

end.