Pfpilot, of course there were horrible abuses in the colonial era. I'm not attempting to sugar-coat it. But let's stick with the topic, the Falklands, and the modern era.
Again, Barbados: "We want to be independent from GB" Britan's reply, "OK, you got it." The Falklands was and is very different. The people of the Falklands want to remain within the British system. So long as the Falklands remain "British soil," any attempt at invasion is going to be met with force.
Mexico lost the States of New Mexico, Arizona, California, and parts of Colorodo and Utah to the USA in 1848. Does Mexico have a "claim" on those States? Here's the thing - those lands were very, very thinly settled in 1848, and the majority of the settlers were anglo-saxon types from the North and East. Right now the population is millions and millions, and they are U.S. citizens heart and soul and have no desire to be a part of Mexico.
Just because Country "A" owned a slice of land 100, 200, 1000 years ago, doesn't mean it is theirs anymore.
We cannot undo all of the land grabs that have taken place hundreds of years ago. All we can do now is listen to the will of the people.