Either PocketBook or FBReader for Android used pie menus in at least some versions. I'd used it on an old Android 5 device where the pie menus were present for

Either PocketBook or FBReader for Android used pie menus in at least some versions. I'd used it on an old Android 5 device where the pie menus were present for some functions. They don't appear on my e-ink Android 10 device. Not sure if that's the device / Android version or an app update. <https://pocketbook.ch/en-ch/app https://pocketbook.ch/en-ch/app> <https://fbreader.org/android https://fbreader.org/android> (Not positive which it was, though I think it was PocketBook. Device is not presently accessible.) As for the pie menus: they were useful in some cases, but aren't a universal panacea for all touch UI problems.