After some time not having bugs in MacOS 10.13 while debugging my app, an error is being thrown at :
As you can see on the screenshot, the error happens at Update Title, and indeed, the error stop happening after uncommenting NSWindowsStyle.Titled.
I was going to wait for an update to complain, but just updated and it doesn't work properlly.
Bug number 2:
The drop down list at the creation of a macOS project, selection of targetting environment is hidden behind the main window.
Only possible to select the correct item with keyboard's arrows.
I am running the preview version, with everything up to date.