The fact that the built-in browser spell check (chrom/ff) is disabled (or not enabled) for tinyMCE editor is very limiting, wherever it is used in the system (KB articles, etc). Mis-spelled words are not underlined, and right-clicking doesn't provide the spell check options. Everything needs to be copied/pasted into an external application (outlook/word) for spell checking, which makes the whole MCE formatting features almost useless since it forces you to reformat everything once pasted back from the external application, not to mention scenarios where you have complex formatting and/or images.
Enable browser spell check in tinyMCE editor - Community / Feature Request - Deskpro Support
I agree that a Spell check option is needed for DeskPro. I am constantly mistyping words and would like to be notified (with an underline or something else) before it is sent out. Or even a Spell Check button that runs a spell check before sending would be helpful.