RFE: touch vertical movement for thumbnails focus on android

First and foremost consider this:

• Only RetroArch bugs should be filed here. Not core bugs or game bugs
• This is not a forum or a help section, this is strictly developer oriented

Description

Currently you can focus on the thumbnail in android with a long touch, however, without the onscreen overlay on the menu, you can't move the focus up and down to the next game thumbnail. Touching the screen again in any place closes the thumbnail focus when the finger is lifted.

Expected behavior

It would be nice if a centered swipe up or down moved down and up, respectively, while still allowing focus exit by tapping the area outside the thumbnail. Not sure what should happen when there is no thumbnail in the middle of the playlist and you're travelling in focus without a indicator a swipe is possible or the thumbnail focus is on.

Actual behavior

You can only close the closeup then move the list with touch, then spend a few seconds on the long touch again.

Steps to reproduce the bug

1. [First step]
2. [Second step]
3. [and so on...]

Bisect Results

[Try to bisect and tell us when this started happening]

Version/Commit

You can find this information under Information/System Information

• RetroArch: [version/commit]

Environment information

• OS: android
• Compiler: [In case you are running local builds]

No file, test, or entry point is named; start by locating RetroArch's Android thumbnail-focus and touch-input handling, then reproduce the long-touch behavior described. Done means a centered vertical swipe changes the focused thumbnail while a tap outside exits focus, with behavior for missing thumbnails clarified.