■ [Ruby-GNOME2] メニューのヘルプ

Sets whether the menu item appears justified at the right side of a menu bar. This was traditionally done for "Help" menu items, but is now considered a bad idea. (If the widget layout is reversed for a right-to-left language like Hebrew or Arabic, right-justified-menu-items appear at the left.)

[GTK+ APIリファレンス：gtk_menu_item_set_right_justified()より引用]

■ とりあえず、Simple Text Editorは直しときました。