Comment 10 for bug 651586

As regards language-selector, its behavior is documented in Natty. You can reach the help document, which e.g. explains the meaning of the greyed menu items in the combobox on the "Language" tab, by clicking the "Help" button when in Language Support.

Furthermore, this is reasonably not a language-selector bug, at least not in Natty, where the list of display languages consists of available translations. I invalidated the language-selector bug.

The use of the word "dictionary" confuses me. The long lists seem to consist of locales, not dictionaries. Maybe there is just one dictionary for Spanish spell checking, for instance. Thunderbird and gedit still show all available locales that relate to the installed languages, which does not make sense IMO.