static/ext/src/form/field/HtmlEditor.js
function() {
                var doc = me.getDoc();
                if (doc.body || doc.readyState === 'complete') {
                    Ext.TaskManager.stop(task);
                    me.setDesignMode(true);
                    Ext.defer(me.initEditor, 10, me);
                }
            }
function() {
                var doc = me.getDoc();
                if (doc.body || doc.readyState === 'complete') {
                    Ext.TaskManager.stop(task);
                    me.setDesignMode(true);
                    Ext.defer(me.initEditor, 10, me);
                }
            }
must defer to wait for browser to be ready