[Bug] Shaders only apply to bottom screen when screen layout is set to 'Hybrid focus top'

Is there an existing issue for this?

• This is a bug in RetroArch frontend
• I have searched the existing issues

Description

Description

When running the melonDS core with the screen layout set to "Hybrid focus top", loading any shader will only apply the shader effects to the smaller bottom screen. The main (top) screen remains unaffected by the shader.

Environment / Platforms Tested

• Core: melonDS (Latest version)

Actual Behavior

Only the bottom screen gets the shader pass; the primary focused top screen renders in raw pixels without the shader.

Expected behavior

Expected Behavior

The selected shader should be applied uniformly across both the top and bottom screens regardless of the hybrid layout.

Steps to reproduce the bug

Steps to Reproduce

1. Launch RetroArch on PC, Android, or Switch, and load any Nintendo DS game using the melonDS core.
2. Open the Quick Menu -> Core Options -> Screen.
3. Change the Screen Layout to Hybrid focus top.
4. Go back to the Quick Menu -> Shaders, enable Shaders, and load any shader preset (e.g., CRT or LCD shaders).
5. Observe the screen: The shader effects are only visible on the bottom screen, while the top main screen has no shader applied.

Version/Commit

1.22.2

Bisect Results

No response

Present in the nightly version

Yes, this is reproduced in the nightly build

Platform & operating system

• Nintendo Switch: Atmosphere CFW (RetroArch Switch v1.19+ / Switch driver) * * Android: Android 13/14 (RetroArch Mobile / Vulkan & GLES3 drivers) * PC: Windows 10/11 (RetroArch v1.19+ / GLCore & Vulkan drivers)

Affected Cores

No response

Environment information

No response

Relevant log output

Reproduce with the melonDS core using the “Hybrid focus top” screen layout, then enable a shader from Quick Menu → Shaders across the listed platforms and graphics drivers. Trace the rendering path for this layout and compare how the top and bottom screens receive shader passes; done means the selected shader affects both screens uniformly.