If a Viewport inside a ViewportContainer is present in the scene, mouse cursor flickers over any LineEdit

[aleksandrbazhin]

Godot version:
3.3 and 3.2.3 stable

OS/device including version:
Windows 10, Nvidia 940GT, GLES2 and GLES3

Issue description:
If there is any Viewport inside a VIewpotContainer in a scene, mouse caret changes from Arrow to Ibeam on move over LineEdits every frame. This behavior maybe too specific, but the report might help when dealing with related issues.
Possible related issues:
#23729
#38633

Steps to reproduce:

• Create a ViewportContainer and a Viewport
• Create a LineEdit anywhere on the same scene
• Hover over LineEdit - cursor flickers (repeatedly changes from Arrow to Ibeam)

Minimal reproduction project:

GodotTest2.zip

[golddotasksquestions]

Can confirm on 3.3.1 stable

[quinnyo]

This happens on any Control (not just LineEdit) with a non-default cursor, as long as the (Sub)Viewport has input enabled. On 3.4.2 and 4.0.alpha2.

[puzzud]

The core of this issue and more or less the network of issues associated with it is easily reproducible:

• Create a scene with a viewport container parenting a viewport.
• Add a button as a sibling to and after the viewport container.
• Change this button's default mouse cursor to a pointing hand.
• Run and move mouse cursor along the button.

If the button's default mouse cursor is restored to the default arrow, this problem (flickering & warping) does not occur.

As mentioned in in the linked Orama-Interactive/Pixelorama/issues/418, monitor refresh rate seems to have an affect. In my case, it seems related to a multimonitor setup where not every monitor has the same refresh rate. For me, they are 144 hz, 75 hz, and 60 hz. I've noticed if I drop all monitors to 60 hz, I don't notice the problem.

Furthermore, I've observed that which monitor the game window launches in as an affect, but it's not always consistently reproduced. If it launches in the 144 hz, it does not have the problem in the 144 hz monitor's display. But if I move the window (without closing) to one of the slower monitors, it does. Contrast with when I launch from the 60 hz monitor--problem exhibits on all monitors, including the 144 hz.

Would this be a computer system issue? I'm using the following:
KDE Kubuntu Linux
OpenGL ES 3.0 Renderer: NVIDIA GeForce GTX 1660 Ti/PCIe/SSE2

But I noticed a Windows NVIDIA GTX user filed the issue I mentioned above.

Lastly, I want to mention that someone above said the issue occurred in 4.0.alpha2 however I cannot reproduce it after converting my Godot 3 test app to a build of Godot 4 from 7/2023 running in Compatibility, which suggests to me that it was fixed at one point. Still occurs with 3.6 beta.

Is there someone who'd have insight as to when this issue might have gotten fixed? Maybe there is a chance to backport it to 3.X.