fix(Desktop): Fix floating sidebar when is mobile colliding with macos

[nalejandroveron]

buttons

What does this PR do?

Fixes the content of the floating sidebar displayed below the macOS window buttons

Closes #8764

How did you verify your code works?

https://github.com/user-attachments/assets/e1fd0ea3-60a1-4c12-86eb-ad6e3079c60c

Checked it in macOS, see my video above

[!CAUTION] Please test on windows and other compatible platforms that have a different window bar, I don't have the hardware to test it, happy to help addressing afterwards