I think it would be very useful to have the possibility to search within the history of the articles of Wikipedia. This way, for example, one could avoid writing something discarded reasonably several times on past editions.
This new feature could be a new namespace box situated next to the ones already avaiable:
(Main) Talk User User talk Wikipedia Wikipedia talk Image Image talk MediaWiki MediaWiki talk Template Template talk Help Help talk Category Category talk Portal Portal talk
I hope this new feature will be soon avaiable in all the language versions of Wikipedia.
Thanks and regards