To improve support, spell checking is enabled by default in the title field of the main window text pane, and some other text fields—such as that for note titles (i.e. $Name). Previously the checking was limited to the $Text area.
It may be toggled by choosing menu Edit ▸ Spelling and Grammar ▸ Check Spelling While Typing. This state is saved with the document.
See also—notes linking to here: