gedit highlight misspelled words for every document by default
Solution 1:
No it can not be set as default.
That does not rule out that someone who knows how to decompile, reprogram and recompile the spell checker plugin for gedit can't make a setting for it, it is open source.
@NIMISHAN: Enchant is a dictionary, and is not responsible for spell checking, nor part of any program. Programs can use it. Even the spell checker in gedit is not part of gedit, just a plugin, plugged into gedit.