The following example displays the Dojo imRichEditor Widget using TinyMCE's Simple Mode. The default theme option for the imRichEditor widget is 'advanced', so you have to set the option to 'simple'. I also changed the set the skin_variant to an empty string. The default is silver.
dojo.addOnLoad(function() {
var txt = 'Hello, how are you';
var ta = new im.imRichEditor({theme: 'simple', editorNode: "tAreas", skin_variant:"", value: txt}, 'tEditor');
});
View the source for this page to view how I setup the widget. For documentation about the Dojo imRichEditor Widget, view my blog post.