[Planet Gemini PDA Questions & Answers] KevReillyUK:
(I'm going to be cheeky and cut-and-paste this (with some edits) from an earlier post on the Gemini Planet Facebook page, so some people may recognise it if you spend time there.)

Since upgrading my Gemini from Android 7.1.1 to 8.1 I've hit a snag with the Amiga emulator UAE4ARM and other emulation apps that use the SDL library for handling video.

It looks as though the new OS may not be providing the correct screen width to whatever function the SDL libraries is using for their fullscreen display. Whether or not the Gemini's navigation bar is hidden, I lose 10% or so of the screen on the right hand side (or the left, if the navigation bar has been moved) when running these apps fullscreen.

All of the apps I've seen this happen to are emulators (UAE4ARM, Vice64 and Unreal Speccy Portable) and while I'm not certain whether Unreal Speccy uses SDL the other two definitely do, which leads me to suspect it as the common factor. The DOS emulator Magic DOSbox uses a different display methodology and works perfectly in fullscreen landscape.

I've tried all available methods for hiding the navigation buttons; Gemini's new settings, UAE4ARM/SDL's built-in Immersive Mode and the Granular Immersive Mode app. All methods exhibit this truncated screen effect. It's interesting to note that in terms of raw pixels, the truncation appears at the same horizontal position that the navigation bar would appear if it were visible. This also coincides with the right side of the titlebar clock, and is only a few pixels to the right of where Planet's own App Bar cuts off, whether or not the navigation buttons are visible.

Everything points to the OS reporting the wrong screen width to certain apps and libraries when the navigation bar is hidden. None of these apps exhibited this behaviour under 7.1.1, but it's unclear to me whether this is a change in Android functionality or a result of something Planet have specifically tweaked for the Gemini firmware (perhaps related to the new built-in ability to hide the navigation buttons?)

I've tried the obvious Google searches but with fairly generic parameters such as "Oreo" "8.1" "width" "SDL" etc. I'm getting a lot of false positives and nothing of actual use.

Does anyone know what might be causing this, and whether there's a workaround to change whatever value the OS is reporting to SDL? I'm pretty sure I've exhausted all of the tweaks available under Developer Options but I don't mind using tools such as ADB to apply tweaks if necessary. I'm even prepared to root the Gemini if that's what's needed, although I'd rather avoid that if possible. I'm really hoping for the equivalent of an .ini or .plist file (you can tell I'm not an Android developer!) that I can tweak.

My next stop will be to contact Planet and let them know, in the perhaps vain hope that this is a simple bug/oversight that they can fix with a later update. The problem with Planet is that their e-mail based support system has no proper feedback channel, so you often don't even know whether your issue has been acknowledged let alone investigated. So I figured I'd run it past the folks in here first, in case I'm missing something obvious.

TIA for any assistance.