When Sweden let go of Norway in 1905 - without war - the border had been stable since 1660 (when Sweden had to let go of Trondheim that it had gained in 1658), and Norway is no longer laying any claims to Bohuslän or Jämtland (though Jämtland has a humorous independence movement). And no one had any crazy ideas about breaking out the Swedish supporting areas, perhaps because the 184 persons who voted no to independence didn't live in the same area. Also, same religion and basically the same language, would have made any strategies to colonise futile.

If Finland hadn't been conquered by Russia in 1809 a Finnish independence movement from Sweden in the 20th century could have been a bloody affair leaving long-lasting scars. Fortunately for Swedish-Finnish relations that wasn't the way history went and the only major dispute over Åland Islands was settled peacefully through the League of Nations. Åland got demilitarisation (including Ålanders not being conscripted) and extensive local rule (including language) which among other things has led to Åland Islands having a seperate treaty with the EU.