WYSIWYG and pre tags

I often post code samples on my blog, and I’ve found the WYSIWYG editor to be a very nice feature, but somehow <pre> tags and the editor don’t seem to get along.

Whenever I post a code example, I paste the code in the editor, then use the ‘Edit HTML’ button to change the p tags to pre tags, and add the leading spaces back that the editor removed. The code shows almost correctly, but without any indentation, it removes the spaces that I added when I added the pre tag to the HTML. I’ve also tried to use &nbsp to add the spaces, those are removed as well.

Is there any way to get it to not trim leading spaces?