Fix r23732.  By the time we get to inner_main it's too late to call gnc_prefs_init.
By then the main window has been created so it doesn't get hooked into the prefs system.
One symptom of this is that the "tab position" pref doesn't affect that window.

git-svn-id: svn+ssh://svn.gnucash.org/repo/gnucash/trunk@23734 57a11ea4-9604-0410-9ed3-97b8803252fd