How to get unity windowed app to remained windowed when maximize

I want my app to always be windowed with a title bar at the top, but if I start it in windowed mode, as soon as I click the maximize button, it switches to full screen with no title bar. From then on I am stuck, you cant change the window size at all. How can I fix this? I am using Unity 2018.3.8f1. It seems to me that in earlier versions of window this worked as expected, so maybe this is a new bug. In the build settings I have tried all possible values of “Fullscreen Mode” but to no avail.

Just did a search of bugs in the issue tracker and have found it listed here: