Unable to simultaneously hold an overlay button and tap the DS tocuhscreen

Description

On an android device with the DS pointer mode set to "touch", holding an overlay button disables the DS touchscreen. This is independent of the core being used - I see it happening on melonds and desmume.
I am certain I have multitouch on my phone. It is possible to press two or more overlay buttons at once, and it is also possible to drag or hold on the touchscreen and press an overlay button. It is only the situation where you are first holding an overlay button and then tap the screen that is unusual.

Expected behavior

It should be possible to hold down a button on the overlay and interact with the touch screen at the same time.

Actual behavior

Holding an overlay button seems to lock the touchscreen, making it only possible to press other overlay buttons

Steps to reproduce the bug

It will likely help to test with a game which relies on this kind of interaction. I discovered it while trying to play Picross 3D for the DS, since that game requires you to hold a d-pad button and tap the screen at the same time.

1. Press and hold any overlay button
2. Tap or drag on the touchscreen area - nothing will happen.

Bisect Results

Unfortunately, I'm not set up for Android development right now, so I can't do any testing aside from on my phone.

Version/Commit

I merely downloaded the latest version of the RetroArch app from the Play Store. When I check Home > Information > System Information, it reports a git version of 4b16b4f.

Start by reproducing the issue on an Android device with DS pointer mode set to touch: hold an overlay button, then tap or drag the touchscreen area. Trace the Android overlay and touchscreen input handling. Done means a held overlay button no longer prevents simultaneous touchscreen interaction, including in Picross 3D.