Fix nested PreferencesPages.
Fix nested PreferencesPages.

elexis/elexis-3-core,sazgin/elexis-3-core,elexis/elexis-3-core,sazgin/elexis-3-core,sazgin/elexis-3-core,sazgin/elexis-3-core,elexis/elexis-3-core,elexis/elexis-3-core