With desktop menu playlist, adding a .zip with a single file inside automatically assumes you want to load that file.

Description

While using the desktop menu, if you want to add to a playlist a .zip with a single file inside, the entry will be modify because it expects you want to load that file inside. It makes sense but it can be really annoying with some cores.

Here's a video I posted on Discord few days ago of me demonstrating how it can mess with Flycast for example: https://cdn.discordapp.com/attachments/434713532341288961/710536650199007242/2020-05-14_18-48-26_edit.mp4

And here's what's going on:

I want to add cvs2.zip to a playlist, the file itself is only ~2KB (it's an arcade game that uses a CHD) and has a single file inside (317-5078-com.pic).
When you add it, the entry is automatically edited to load /path/to/rom/cvs2.zip#317-5078-com.pic. And because of that, Flycast will try to load the .pic file inside instead of the whole .zip and will fail...
If you edit the entry to remove #317-5078-com.pic it doesn't work, RetroArch will re-add it automatically.
As a simple workaround I add a dummy file inside the .zip, with this the file is no longer alone and RetroArch adds the .zip properly.

My suggestion would be maybe add a "Load as a zip file" box to check or something like that when adding an entry? Something like this:

Steps to reproduce the bug

1. Start desktop menu and in a playlist add any rom zipped with a single file in it.
2. Once it's added, edit the entry and you'll see rom.zip#rom.extension.
3. Delete #rom.extension from the "Path" field and press "OK".
4. Edit the entry again, the #rom.extension should be back...

Version/Commit

• RetroArch: 1.8.7 / 582f967fb0

Environment information

• OS: Windows 10

Start with the desktop menu's playlist add and edit flow described in the reproduction steps, tracing where a single-file .zip becomes a path with a #member suffix. Reproduce with a zip containing one file, then verify that adding it preserves the zip path and that editing and reopening the entry does not restore the suffix.