How to get the instance of the fckeditor in a command plugin

Hi,all

I have a trouble.
I am adding a command plugin.
I want to get the instance without the id of the fckeditor in the fckplugin.js

Here is the aspx code.

<FCKeditorV2:FCKeditor ID="FCKeditor1" runat="server" BasePath="/Test/fckeditor/" ToolbarSet="Basic">
</FCKeditorV2:FCKeditor>

I know several methods,like:

var Editor = FCKeditorAPI.GetInstance('FCKeditor1');
var Editor = window.parent.InnerDialogLoaded().FCK;
var Editor = window.FrameName.FCKeditorAPI.GetInstance('FCKeditor1');
var Editor = opener.FCKeditorAPI.GetInstance('FCKeditor1');

But only the second one doesn't need the id,and the second one is the method using in the dialog window.
If I make the id changeless,then when I change the id ,the plugin doesn't work.

So I want to know if there is any way to get the instance of the fckeditor when I add a command plugin?
can anyone help me?