Hi,
If I were trying to show code in a MODx page, I wouldn’t even use Tiny. WYSIWYG editors in web browsers, no matter how good they are, tend to be evil.
True, you can try using the HTML edit button and all that, but Tiny will add its own code to what you do in a whole lot of situations. It thinks it’s doing you a favor.
I would suggest editing the page, under Settings uncheck Rich Text, Save, and then edit the page using raw HTML, including <CODE> tags, or whatever makes your code look good. Some manual work, for sure, but if you write code, you might not mind.
I have a battle with clients all the time who just can’t believe that the WYSIWYG editor can’t do exactly what is in their MS Word document.
Good luck, Dave