Just guessing, but probably a tribute to the first game Harolds Club offered opening day, 2/23/36. Penny roulette (note ¢ signs on front of the "store") as Harold Sr. describes it in his book I want To Quit Winners:

"The game we set up used one eight-foot wheel suspended from the ceiling with a gigantic mirror and 43 layouts for players. This way, the player could sit down before a layout of four narrow columns of numbers, place his bets and watch results as the wheel lit up the numbers. This "flasher" wheel, as they are known, was the first introduced in Nevada."

Not exactly a great description, but the gizmo in the window doesn't look like a wheel of fortune affair either so perhaps a flasher wheel dealie-bobber? The rest of the section tells of 21 being added that fall and craps in '37.

I'd be interested to know what the window sign on the left says, "???? Bank"? and if you can read the legend on the end of the fixture just inside the door?