This is a distillation of a problem reported against SunStudio where 
if the locals view is sorted by Name, with each step the sort order 
reverts to unsorted, even though the column indicates sorting
(using the v or ^ icon).


NB itself when debugging Java also has a variation on this problem.
Two examples:
Enable sorting by name in the java debugger locals view.
1 step through some code which has local declarations in the middle of a block.
  Unlike sunstudio with each step the sort order is maintained.
  But as you step over the stmt which has a local declaration and that variable
  gets added to the locals view it gets tacked on w/o consideration of sorting.

I suspect that jpda's local variable objects don't get re-added on each
step which is why this bug isn't very noticable. In SunStudio we get a fresh list
on each step and replace the "model". This theory can be confirmed with
another experiment:

2  stop in some deeply nested function, enable sort ordering for locals.
   as you move and and down the stack the sort order isn't maintained.
   presumably because the locals view model gets changed as one moevs
   around stack frames.

This adds credence to the theory that viewmodel doesn't re-sort 
when the model drastically changes.