That window with Code and Initialization code tabs is the CB editor, you're all right. It doesn't work for some other reason then. I don't have fx3 and can't tell if the buttons below will work but give it a try:
This one opens files and folders. They're pre-coded there but you can edit the code to point only to word.exe, notepad.exe, wordpad.exe.
Delete everything between 'menu items' lines and insert your paths (don't forget to switch the slashes! '\' to '/' !!). Change the items names (apps.push(['YOUR OWN ITEM NAME HERE', see my example below). It should then look something like this:
//------menu items--------
apps.push(['WordPad',folderImg,'c:ProgramFiles/Windows NT/Accessories/wordpad.exe']);
//------/menu items-------
The only reason i don't like this button is that it pops 'Done' alert every time you edit it and restart Fx. But it just needs to be updated, i think. Maybe whoever knows what they're doing can do this ... sometime.
Here's link to a thread about a
single folder button. Maybe it will help? You can create the button yourself and see if it'll work in Fx3.
I use the Browse Folder button which you can find in my buttons list if you click on the (3) circles icon under my name --->
It works for me.
BTW, i hope you created a new profile to use with Fx3. I see problems posted all over forums when people try to use fx2 profile(-s) with Fx3.