r21187: - Convert LdbBrowse to use TreeVirtual. This adds the following capabilities

r21187: - Convert LdbBrowse to use TreeVirtual.  This adds the following capabilities
  that Simo asked for:

  * One can now open a branch without selecting the row.  The previously
    selected row (if any) remains selected.

  * Selecting a row does not automatically open the branch.  That can be done
    by either clicking on the open/close button or pressing Enter while that
    row is selected.

  * The entire tree can now be disabled.  In LdbBrowse, the fsm is configured
    to disable the tree during each remote procedure call, so that a pile of
    requests don't get queued during RPC.

  The most obvious flaw with TreeVirtual right now, is that the tree does not
  properly resize (or even initially size itself) to its container.  Fixing
  that is my next task.  It's actually a generic Table issue that people have
  been asking for for ages: having columns resize themselves automagically.
(This used to be commit 23a8b777638f7f40d95e125de97d077ae964e796)