Preserve index while browser window is created

In Mono, the window for XmlBrowseView is apparently created after the
SelectedIndex has been set from the persisted properties.  During the
processing, MakeRoot() is called, which resets the index to zero.  This
changeset fixes FWNX-1076.

Change-Id: I1922e6bf7116edb2964a7ddc11bc5c75e6bbbf1d