> This doesn't seem to be reported by others but if grid refresh anomalies are experienced, losing and restoring focus may be a very low-cost experiment/remedy.

The other reason was that grid, ahem, behaves while it has the focus, it selects its recordsource, visits records as it refreshes etc, and if happens while you do some other processing, you may get funny glitches. Taking focus off the grid was the way to avoid grid refreshes while processing.