get_final_transform() does not return the complete transform of a Window

[Sauermann]

Godot version

v4.0.beta.custom_build [e69b708]

System information

Linux

Issue description

According to the documentation of Viewport::get_final_transform it should: "Returns the total transform of the viewport."
When used on a window, this function does not contain all transforms of a window, so users can not convert between the coordinate system of the window's embedder and the coordinate system of the window's viewport (#30950 (comment)).

The following picture shows the MRP:

Displaying the final transform of the three windows (from left to right) results in:

Window [X: (1, 0), Y: (0, 1), O: (0, 0)]
Window2 [X: (2, 0), Y: (0, 2), O: (0, 0)]
Window3 [X: (1, 0), Y: (0, 1), O: (0, 0)]

The problem becomes apparent for Window2, which misses the vertical translation for the upper black bar.

Steps to reproduce

Load and run MRP

Minimal reproduction project

BugWindowFinalTransform.zip