interface
 
uses
  DesignIntf,DesignEditors;
 
type
  TMyClassProperty = class(TPropertyEditor)
  public
    procedure Edit; override;
    function GetAttributes: TPropertyAttributes; override;
  end;
 
procedure Register;
 
implementation
 
uses
  MyClassUnit;
 
procedure TMyClassProperty.Edit;
begin
  with TMyDialog.Create(nil) do
  try
    ShowModal;
  finally
    Free;
  end;
end;
 
function TMyClassProperty.GetAttributes: TPropertyAttributes;
begin
  Result := inherited GetAttributes + [paDialog];
end;
 
procedure Register;
begin
  RegisterPropertyEditor(TypeInfo(TMyClass),nil,'',TMyClassProperty);
end;