Standard way to pass coordinates to plugins

Standard way to pass coordinates to plugins

We've got a ticket for creating a standardized way of passing coordinates/positions to plugins ( <a href="http://dev.jqueryui.com/ticket/2525"> http://dev.jqueryui.com/ticket/2525</a> ).  This was put on hold until we had a positioning plugin.  Now that the position plugin is in trunk, we should tackle this.  I've created a ticket to make dialog use the position plugin ( <a href="http://dev.jqueryui.com/ticket/4716"> http://dev.jqueryui.com/ticket/4716</a> ) and attached a patch.  Before committing that change, I'd like to figure out our standard way of passing positions to plugins and make sure this will work across the board.
We've got an interesting situation with the three use cases outlined by these tickets:
- Position does not (currently) allow mixing pixel values with words (left, right, top, bottom, center).  There are separate options that deal with words (my, at) and pixels (offset).
- Dialog's position option accepts a string or an array and allows specifying either words or numbers and they can be mixed.  The previous version didn't support specifying multiple values with a string, just short forms like "left" or "top" and would default the second value to center, which is the same behavior as passing a single value to the position plugin.  My patch for dialog allows users to specify two values using a string or an array (accepting an array is needed for backward compatibility).
- Draggable's cursorAt option only accepts pixel values.  This could be extended to support words if we wanted it to.
So, what are everyone's thoughts on how we should handle this?  Should we always only accept string, only arrays, always accept both?  My vote is for accepting both, should only be a few small tweaks to make the position plugin work with arrays.  I would also vote to support mixing words and pixel values when only one value may be provided (dialog's position option and draggable's cursorAt both fall in this category).  Anything that accepts multiple values (this should really only be limited to the options hash for the position plugin) can be decided on later when we add more functionality to the position plugin.