Starting applications, `open` vs mouse click
Apple developer info for 10.14 and AppKit had enough info to find the issue.

What mattered in this case was that the call order is slightly different depending on open Application.app or clicking on it. So do not assume call order for the first calls anymore. 

The breaking change was that resetCursorRects (from NSView in AppKit) now can be called before the first redraw. AFAIK this was not the case previously.

See 
https://developer.apple.com/documentation/appkit/appkit_release_notes_for_macos_10_14?language=objc