I think it would be nice to be able to use the variable $size when the switch $tpl_type = 'select'
With this modification we can unselect a value without needed to create our own function for adding a choice like "No Value" or "None"
How to use it ?
In ACP file used the 'select' type as below :
For example define the size to '8'
After, on submit, we check if no value is selected by using the following code