Well, I don't think the Spanish have any moral authority to question British ownership of Gibraltar until they pull out of Ceuta and Melilla. And I wouldn't think of asking them to.
In the case of gibraltar, spain signed a treaty ceding it to great britain (and maybe NL? dunno). If a treaty between 2 sovereign powers isn't considered a binding document, what is?
The same could be said about the Panama canal. Regardless of the intelligence behind the 79 treaty, once it was done, it had to be fulfilled, despite the wish of some on FR for the US to 'take back' the canal. The neutrality clause is something that would only be invoked in a matter of grave and IMMEDIATE concern, due to the fact it would probably be the death knell of the standing government in Panama in the next elections.