RE: [PATCH:MI] Return a subset of a variable object's children

["Marc Khouzam" <marc.khouzam@ericsson.com>]

> > > I was thinking that only a small number of children would ever exist
> > > simultaneously.  Scrolling might make that a larger number but maybe
> > > it could be arranged to delete children that go out of view.
> > 
> > I wonder if deleting children that are not visible is possible/desirable.
> > In Qt, item data is requested only when item is drawn. I think SWT's Tree
> > can be configured the same way. However, I don't think I saw any way, in
> > either, to detect than an item is no longer visible. Marc, can you tell if
> > SWT allows that?
> 
> In Emacs I would just find the first and last line numbers and work out
> which elements were displayed from that.  

I'm not sure what SWT allows...
In DSF-GDB, we have a LeastRecentlyUsed queue which allows us to know which
varObj is the oldest (which implies it is not visible), and we can deleted
once we have reached our limit of 1000 varObjs.

I still think that GDB should avoid having the requirement of 'deleting
old varObjs' toward the frontend.  It would be nicer if GDB would keep
its efficiency, not matter what the frontend did in this case.