The Valdiation callout windows have some useability problems. 

This can be an umbrella issue for more specific improvements that can be
described in other more detailed issues.


The most significant problem is that when more than one callout window ovelap,
the readability is not so good.

Possible improvments include

- Changeing to modal style so that only one callout is opened at a time and when
user opens one, the last opened callout is automatically closed.

OR improving the multiple callout useability by

- Adding a "stack" model to the callouts - so that when user clicks on the
border or background of a partially hidden callout, it raises to top of stack


Other possible improvements

- Line item folding - allow user to "fold" the details of a particular line
item. This is deiriable for those long validation error messages generated by
the XML validator.

- Maximize window action to allow callout to be resized to show entire contents
so that user does not need to scroll

- Drag/Move action to allow user to move callouts around for better readabilty.
This raises possoble problem for persistence. The next time callouts are
rendered if they are back in origianal position user may get frustrated.