For the last few hours i've been going through the examples and trying out various aspects of the Scriptaculous javascript framework. I've tried numerous ways of doing the sorted drag and drops but i'm stuck on a little issue at the moment and I can't find any information on it.

Could anybody offer any help or point to resources on how I can lock an item in the sortable list? For example, just say I have 7 items in a sortable list but I want to lock the first item to only be allowed in the first position, giving an error or saying item cannot be moved to such a position if you try and move it. Or for another example having 2 columns with sortable lists and with some items restricted to only one column whilst others can be moved back and forth. How would I go about doing something like that?

Any help is appreciated. Thanks in advanced.