Works perfectly now, thanks!
I discovered another strange quirk with Kodi today. I'm using PreShow to trigger Kodi's Vertical Shift to move the screen down to the bottom mask. However, the Vertical Shift function behaves differently with different frame rates, even on files with the same aspect ratio. For example, a 2.4:1 movie at 23.97 fps requires a Vertical Shift of setting of 0.98 down to bring it to the bottom edge, while a 2.4:1 movie at 24 fps requires a Vertical Shift of 1.13. And odd conundrum, since I can't select fps from PreShow's Conditions. Is it possible to add such a condition, or do you have any other ideas?