Right I have noticed an issue with the way Product Types are handled. Thought I'd post here just in case any body have the same issue.
I tried to get another sidebox working based upon what DrByte said above.
When I enabled the sidebox and changed the id for my new product type I got a Non-Object error from the category_tree class. This was actually relating to the database object within the class. It appears to have been being caused due to an error in SQL query on Line 25
PHP Code:
$sql = "select type_master_type from " . TABLE_PRODUCT_TYPES . " where type_master_type = " . $product_type . "";
Changing the SQL query to this resolves the issue:
PHP Code:
$sql = "select type_id from " . TABLE_PRODUCT_TYPES . " where type_master_type = " . $product_type . "";
Oh and also change the following:
PHP Code:
$master_type = $master_type_result->fields['type_master_type'];
For:
PHP Code:
$master_type = $master_type_result->fields['type_id'];
This appears to have resolved the issue for me!