Here at Skynet, we use a lovely little date picker script written by monkeyphysics (no real name on his site that I could find). You can find the original script including a donate link for the author and licensing here: MONKEYPHYSICS MOOTOOLS DATEPICKER
All of the sudden, the modern browsers decided to create an issue that caused picking dates in the past to be very glitchy. DJ described it by saying It really is like one of those whack-a-mole games.
Honestly, I think the so-called glitch should have been a problem from day one. The script renders two different divs at the same time, and it simply just hides the inactive one. I added a z-index so that the visible one would be on top. Without this, it was hit or miss how the click event would bubble.
It was a very easy fix. I added the following lines of code on line 299, pushing what was on line 299 below the added code.
You can just add them yourself or download an updated copy here:
Source: Skynet Solutions
By: Jed Parmenter