Finished theme manager to the point where it's in a working state in Firefox and hopefully IE.
(function(){tinymce.create('tinymce.plugins.Nonbreaking',{init:function(ed,url){var t=this;t.editor=ed;ed.addCommand('mceNonBreaking',function(){ed.execCommand('mceInsertContent',false,(ed.plugins.visualchars&&ed.plugins.visualchars.state)?'<span class="mceItemHidden mceVisualNbsp">·</span>':' ');});ed.addButton('nonbreaking',{title:'nonbreaking.nonbreaking_desc',cmd:'mceNonBreaking'});if(ed.getParam('nonbreaking_force_tab')){ed.onKeyDown.add(function(ed,e){if(tinymce.isIE&&e.keyCode==9){ed.execCommand('mceNonBreaking');ed.execCommand('mceNonBreaking');ed.execCommand('mceNonBreaking');tinymce.dom.Event.cancel(e);}});}},getInfo:function(){return{longname:'Nonbreaking space',author:'Moxiecode Systems AB',authorurl:'http://tinymce.moxiecode.com',infourl:'http://wiki.moxiecode.com/index.php/TinyMCE:Plugins/nonbreaking',version:tinymce.majorVersion+"."+tinymce.minorVersion};}});tinymce.PluginManager.add('nonbreaking',tinymce.plugins.Nonbreaking);})();