Tabbed windows were one of the advertised additions to Max 8: "Max 8 is compatible with modern Mac OS full screen windowing features including tabbed windows". And they are great, I was planing to use them all the time, but there is one annoyance, which makes usage of tabbed windows really difficult (I'm on Mac, MacOS Mojave).
It turns out, that if there is more than one tab open, the Max window grows in size after every opening/closing the sidebar (inspector, console, reference, search etc). Opening Max sidebar changes the Max window width: after several sidebar usage the Max window grows to the entire screen width.
Here is a quick video to illustrate the issue
(I just press keyboard shortcut combination 'Ctrl+N, Ctrl+M, Ctrl+W' sequentially (new window, open sidebar, close window). The widow grows to the entire screen width on the third iteration).
I contacted Cycling'74 support, describing this issue and they answered: "In Max, tabs are only supported in full-screen mode, so if you try to use them when not in full screen you will encounter issues such as this." This sounds strange to me. Can this behaviour be fixed in not full-screen mode?