As it stands now, this would not be trivial to implement since GTK+ doesn't provide any type of spell checking functionality for any of its widgets. libsexy has SexySpellEntry but using that would add two library dependencies: libsexy and libenchant. Adding two libraries for a small feature is in my opinion an unacceptable option. And I doubt SexySpellEntry will be merged into GTK+ for the very same reason we won't use it (depending on libenchant).
Having said that, this seems like a good candidate for a plugin if we ever implement a plugin system (bug 279503).
As it stands now, this would not be trivial to implement since GTK+ doesn't provide any type of spell checking functionality for any of its widgets. libsexy has SexySpellEntry but using that would add two library dependencies: libsexy and libenchant. Adding two libraries for a small feature is in my opinion an unacceptable option. And I doubt SexySpellEntry will be merged into GTK+ for the very same reason we won't use it (depending on libenchant).
Having said that, this seems like a good candidate for a plugin if we ever implement a plugin system (bug 279503).