Flexinode: limit file size &/or extensions in "add file" list

Hi.
It's about flexinode module.
When you go to "content | content type" (and after creating a custom content type), you will see this "add file" list.

When you click on it, you can set the properties of the "add file". However it doesn't have:
- file size limit
- file extension limit

Does anoyne know how to add these 2 functions in the "add file" list?