Lawrence Gordon Tesler (born April 24, 1945) is a computer scientist who works in the field of human–computer interaction. Tesler has worked at Xerox PARC, Apple, Amazon, and Yahoo!.
Tesler has a strong preference for modeless software, in which a user’s action has a consistent effect, rather than changing its meaning depending on previous actions, as in the vi text editor. His Gypsy editor, for example, provided a ‘click and type’ interface in which the user could, at any time, enter text at the current insertion point, or click where the insertion point should be repositioned. Previously, most editors used the keyboard to enter text or to issue commands, depending on the current mode. To promote his preference, as of 2010, Tesler equipped his Subaru automobile with a personalized California license plate with the license number “NO MODES”. Along with others, he has also been using the phrase “Don’t Mode Me In” for years, as a rally cry to eliminate or reduce modes.