Legs

Where does the expression that something "has legs," meaning an idea or project that is practicable, come from? I have the idea that it is an expression of the movie industry, but I don't know.

Originally in the late 19th century it was racing slang; a fast horse or greyhound was said to "have legs". Obviously a fast racing greyhound or horse is likely to win races, so the phrase was employed by the communications media with the sense "have the potential for success". (VSD)