Illustration of a String becoming a WideString
Last updated at 10:32 am UTC on 16 December 2015
'abc' inspect
http://www.unicode.org/charts/PDF/U0000.pdf

'aäbc' inspect
http://www.unicode.org/charts/PDF/U0080.pdf

('aäba', 16r0308 asCharacter asString) inspect
http://www.unicode.org/charts/PDF/U0300.pdf

('aäba', 16r0308 asCharacter asString) allButLast

('baa' at: 3 put: 16r0308 asCharacter; yourself) inspect

Eliot Miranda (Dec 2015, ML):
In Spur, #become: is cheap so this growth pays only for the reallocation and copying of the at a, not for an expensive heap scan necessary to do the #become:.