[Axelay] Graphical glitch / broken horizontal sky background layer

[detectorcaleta1]

There is a graphical glitch in Axelay (Stage 1) when using the Snes9x core. The horizontal sky background layer near the top of the screen appears broken, split, and misaligned on the left and right edges.

Steps to Reproduce

1. Launch RetroArch on Windows.
2. Load the Snes9x core.
3. Start Axelay.
4. Progress into Stage 1 and observe the horizontal sky background layer at the top.

Expected Behavior
The sky background gradient should render seamlessly across the entire width of the screen without any horizontal gaps, misalignment, or tearing at the edges.

Actual Behavior
The sky layer looks split or broken horizontally near the edges, creating a noticeable visual glitch.

Environment
OS: Windows 11 Pro and Android (Motorola Moto G Stylus 2025)
Frontend: RetroArch 2026-09-05

Additional Context
This exact same issue occurred years ago in the Snes9x 1.60 standalone emulator and was previously fixed. A recent update to the core seems to have reintroduced this regression in the sky background, specifically visible during the first stage of Axelay.

[ToniBC]

I have the same problem; these lines appear on the right and left sides of the screen, at the top of the background, which didn't appear before.

[detectorcaleta1]

Hello, I am adding another screenshot of the issue.

[Tatsuya79]

I can confirm this bug wasn't there prior to the August commits.

Tested on 185488c (before #303 that was breaking the input, axelay was fine with it too) win10 x64.

[LibretroAdmin]

Pushed acommit, check it out

Tested Axelay on both and that visual issue doesnt happen anymore at least

snes9x 2010 has also been updated, it shouldnt happen there anymore either

[Tatsuya79]

Can confirm it's fixed.

[LibretroAdmin]

@ToniBC @detectorcaleta1 If either of you can confirm it's fixed for you as well, I feel comfortable in closing this issue