Comment 23 for bug 135985

All right, I re-commit the patch

http://bazaar.launchpad.net/~muzuiget/exaile/exaile/revision/4357

Note that I have to change xlgui/preferences/__init__.py one line "show_all()" to "show()". The PyGTK document says "The show_all() method recursively shows the widget, and any child widgets (if the widget is a container)." So "show_all()" will break the "visible" property in ui file.