gtk3: GTK_TYPE_LEVEL_BAR is a GObject
gtk3: GTK_TYPE_LEVEL_BAR is a GObject

So, use GTK_LEVEL_BAR(RVAL2GOBJ(o)) instead.

kitachro/ruby-gnome2,kitachro/ruby-gnome2,kitachro/ruby-gnome2,kitachro/ruby-gnome2,kitachro/ruby-gnome2