I don't think Semie invented the zero fret. If you look at his triple neck from 1956 none of the necks have a zero fret. Chet Atkins asked Gretsch to incorporate the zero fret in 1959. Django Reinhardt preferred zero fret guitars in the 1930's - 1953 when he died. He was playing a French made guitar in the late 1920's early 1930's with a zero fret. Scroll down this page and you'll see a guitar with a zero fret made probably before Semie was born.
http://www.djangomontreal.com/doc/Pictures.htm"Zero Fret
This "feature" used a fret as the actual nut (though there was a nut too for guiding the strings to the tuners only). Gretsch called this their "Action-Flo" nut.
Chet Atkins models: 1959 and later.
Duo-Jets: 1962 and later.
White Falcon, Country Club: 1963 and later.
Sal Salvador, Astro jet: 1965 and later.
Viking, Anniversary, Rally, Broadkaster, Rancher: 1968 and later.
Clipper, Corvette: never got a zero fret."
http://www.gretschguitars.com/resources ... tions.htmlAction-Flow™ Zero Fret Nut
Introduced in 1959, the Action-Flow Zero Fret Nut allows you to play at fret level from one end of the fingerboard to the other. No more string nuts that are too high or too low!