Reworked the base_selector definition and modified all references to it.
Added the disabled state to base_selector and base_spinbox.

modified:   base.xml
modified:   browser-ui.xml
modified:   config-ui.xml
modified:   gallery-ui.xml
modified:   music-ui.xml
modified:   musicsettings-ui.xml
modified:   mytharchive-ui.xml
modified:   mythburn-ui.xml
modified:   schedule-ui.xml
modified:   stream-ui.xml
modified:   video-ui.xml