[iPadOS] Full screen mode in external display on iPadOS not supported

Description

RetroArch doesn’t support full screen in external display on iPadOS.

Expected behavior

With the appropriate cable and/or adapter, you can connect iPad to a secondary display, like a computer display, TV, or projector, where you can view the iPad screen. If you then go to iPad’s Settings > Display & Brightness > Arrangement and turn off Mirror Display you can use your secondary display with its native aspect ratio without getting black borders when running apps full screen.

In order to run an app full screen in secondary display, you first must move the app to the external display by clicking three dots on the app’s title bar and selecting Move to Display or simply dragging the app window. Then you can put app to full screen mode by dragging from the app window corners (with mouse pointer obviously as your working in external monitor without touch controls) all the way to screen corner or using keyboard shortcut Globe Key + F (on Apple Magic Keyboard).

Actual behavior

RetroArch on iPadOS doesn’t support full screen mode in external monitor. You can resize the app window to different sizes but it won’t go full screen meaning you will always see desktop on background that somewhat ruins the gaming experience.

As shown in screenshots below taken from a monitor wired to an iPad, RetroArch only runs in windowed mode whereas many other apps (in this example Reddit) can be run full screen.

Steps to reproduce the bug

Follow the steps described in the beginning of this post.

Bisect Results

Don't know if this feature ever existed in RetroArch for iPadOS.

Version/Commit

You can find this information under Information/System Information

• RetroArch: 1.19.1

Environment information

• OS: iPadOS 17.6

Start by reproducing the behavior on iPadOS 17.6 with RetroArch 1.19.1 using an external display and non-mirrored arrangement. The issue names no files, tests, or entry points; identify the iPadOS external-display and window-management code, then verify that RetroArch can enter native full-screen mode without desktop borders.