Subviewport's push_input does not do object picking

[krdluzni]

Tested versions

• Reproducible in v4.3.dev5.official [89f70e9]
• Not reproducible in v4.3.dev4.official [df78c06], v4.2.1.stable.official [b09f793]

System information

Godot v4.3.dev5 - Windows 10.0.22631 - Vulkan (Forward+) - dedicated NVIDIA GeForce RTX 4090 (NVIDIA; 31.0.15.5123) - AMD Ryzen 9 7950X 16-Core Processor (32 Threads)

Issue description

When receiving an input event and using push_input to pass it to a SubViewport (that has physics_object_picking set to true), 3d objects do not receive the expected mouse events.

Steps to reproduce

With MRP:

• Open MRP and run.
• Click left cube and see that it rotates.
• Click right (blue) cube and see that it does not rotate.
• Note that the right cube is being displayed through a SubViewport rendered onto a Sprite2D, and input events on the sprite are being pushed to the SubViewport via push_input.
• Note that this did work in 4.3.dev4

From scratch:

• Create a scene with an Area3D (and a matching visual aid) and hook up a print statement to the input_event, mouse_entered, mouse_exited signals. Add a camera to the scene and point it at the Area3D.
• Wrap the scene in a SubViewport with physics_object_picking enabled.
• Create a TextureRect outside the SubViewport and set it to display the SubViewport's ViewportTexture.
• Add an input handler on the TextureRect, and pass the received input to the SubViewport via push_input.
• Run the scene and note that the signals are not received.

Minimal reproduction project (MRP)

https://github.com/godotengine/godot/files/11975240/SubViewportAndMouseAreaWithChanges.zip, originally posted in response to #79128 as a demonstration of how to propagate input events to a SubViewport is a good demonstration of the behaviour.

One of the cubes rendered is in the scene directly, the other is in a SubViewport having events pushed to it. If you click the cubes, they should randomly rotate themselves. In 4.3.dev4 and earlier, they do. In 4.3.dev5 the one in a SubViewport does not.

[Sauermann]

Thank you for the report.
This change got introduced by #88992.

A way to mitigate this is shown in this project: SubViewportAndMouseAreaWithChangedChanges.zip
Make sure, that the SubViewport receives mouse-entered/exited notifications, when the mouse enters/exits the sprite.

Since this problem has already been reported in #89757, I will consolidate this issue as a duplicate with #89757.