From a rudimentary reading. They introduced a state cache to fix conditions where applications poll continuously for certain states (mouse button press for exa

From a rudimentary reading. They introduced a state cache to fix conditions where applications poll continuously for certain states (mouse button press for example). This wasn't thread safe however, and multi-threaded applications could get a previous/incorrect state back from the cache and stop functioning as intended. This was highly visible for photoshop tools where you click and hold, as the separate mouse poller thread would get a state of 'button not clicked" and stop, or in some cases start/stop repeatedly giving a series of dots instead of a line. The patches submitted early were to disable the global cache, which while it fixed the multi-threaded use cases didn't fix the high-polling rate issue that the global cache was attempting to fix. The fix, years later, was to look at the global cache when changing state and invalidate it at the time of state change so any immediate calls to retrieve that state from the cache will not get the previous cached state. There was also another issue that came up in the middle of that thread that was unrelated it seems.