Today, April 2nd 2017 is the 35th anniversary of the start of The Falklands War. The Argentine claim is presumably based around proximity only because they have no real legal claim, none; to be honest, not even proximity applies really.
Now another Spanish-speaking nation is rumbling about a territory that it has no real claim to (but at least they used to own it for more than a couple of months); unfortunately for them the Mons Calpe - one of the 'Pillars of Hercules' - the 'Mountain of Tariq' was formally ceded to the British Crown as part of the Peace of Utrecht. British sovereignty over Gibraltar was confirmed in two later 18th Century treaties.
"The Catholic King does hereby, for himself, his heirs and successors, yield to the Crown of Great Britain the full and entire propriety of the town and castle of Gibraltar, together with the port, fortifications, and forts thereunto belonging; and he gives up the said propriety to be held and enjoyed absolutely with all manner of right for ever, without any exception or impediment whatsoever."There is no case to answer; there is no reason to sell, gift, combine sovereignty or change the current status of Gibraltar at all, in any way: time for the Spanish government to stop azotando un caballo muerto, or as they might say, dar patadas de ahorcado.
Part of Article X, Peace and Friendship Treaty of Utrecht between Spain and Great Britain (1713)