Checking where is the selection node ?

Hi,

I have a command that add a specific piece of HTML at the selected area.

CKEDITOR.instances.editable.addCommand('button_cmd', {
                                               exec: function(editor) {
                                               editor.insertHtml('<div class="btn">mybuttoncode</div>');
                                               }
                                               });

I would like to cancel the actio if the selection is already in a element with a 'btn' class.

I made this functions :

        function isDescendant(parent, child) {
            var node = child.parentNode;
            while (node != null) {
                if (node == parent) {
                    return true;
                }
                node = node.parentNode;
            }
            return false;
        }
        
        function isInAButton(node) {
            var butts = document.getElementsByClassName('btn');
            for(var i=0,j=butts.length; i<j; i++) {
                var butt = butts[i];
                if (isDescendant(butt,node)) {
                    return true;
                }
            }
            return false;
        }

But document.getElementsByClassName('btn')  is always returning 0 elements, even if I already inserted btn's.

Why 'document' doesn't show me the real content of the editor ?

Thanks