In the documentation for Draggable, one option for the containment syntax is given as (top, left, width, height). This is also replicated in the comments header as (topm left, width, height) -- presumably 'topm' was intended to be 'top' followed by a comma.

In fact the order of these position elements is incorrect, and should be (left, top, width, height) to match the code (see line 259 in idrag.js).