firefox, range doesn't work

I want to move the input cursor to the end of the editor body, but I found it didn't work in firefox!

I tried like this in js:

//my editor name is htmlEditor
var editorDoc = CKEDITOR.instances.htmlEditor.document;
var range = new CKEDITOR.dom.range(editorDoc);
range.moveToElementEditEnd(editorDoc.getBody());
range.select(true);

it worked in IE, but not in firefox, who can help me?
sorry for my poor English!
thanks a lot!
gaoht