Some of the coolest features of the Mac OS often go completely unnoticed. In reading through a post at Mac OS X Hints, I came across this little gem regarding Mac OS X Snow Leopard’s built-in grammar checker.

Grammar tool tip in Mac OS XIn many Cocoa apps (or another app that supports the feature), a green dotted line is placed under possible grammar errors detected by the system. If you hover your mouse cursor over the underlined word, a tool tip pops up describing the error. The screenshot you see here is from TextEdit, where I’ve made the horrific error of forgetting to capitalize the first word in the sentence. To accept the correction, you can either right-click and accept the correction in the contextual menu, or inside the spelling and grammar dialog box accessed from the contextual menu.