Did you know that System Preferences is a 64-bit application? Stands to reason, but one thing I realized recently while working on some code for a System Preference pane is that 32-bit System Preferences cause System Preferences to react differently. You can use 32-bit preference panes but using them prompts you to quit System Preferences, which relaunches into a 32-bit mode. Going back to 64-bit mode also requires a relaunch. This is a great reason for developers to get their code upgraded sooner rather than later as I can’t imagine this compatibility mode will last forever…
