Open multiple sketches at the same time

Am I missing something? I can't seem to open more than one sketch at a time using the new IDE, currently beta 7. With one sketch open, using New or Open or Open Recent closes the current sketch and opens the selected one instead.
It would be really useful to have more than one sketch open at the same time in separate windows when using code from one sketch to inform another.
I'm using a Mac running Big Sur 11.3.1.
I'm sure this has probably been reported already but couldn't find any entry in the forum.

Works OK for me on Windows 10

An example. I started the IDE then did File, New and a second edit window opened. What may have confused you is that the second window is opened at the same size and position as the original one, so at first sight the original one seems to has disappeared

Works OK for me on Windows 7 and beta 6, just like @UKHeliBob wrote.

I also have never seen the reported behavior. However, I've only made any significant use of the IDE on Windows and Linux. I do have a macOS machine that I break out when absolutely necessary, but it's very inconvenient and other members of the IDE's development team are primary Mac users so I don't end up doing it often.

I rarely only have one window open at a time. My frustration is that they can't have different tools. (Port, board ,etc).
I also don't run an experimental IDE. (Or a Mac. In fact, I've never touched a Mac.)

IDE 2.0 appears to have lost the ability to have more than one instance open unlike the classic IDE

Is this by design or just an oversight ?

Every Arduino IDE 2.x window is independent. There's no longer any need to jump through hoops to get that behavior like with the classic Arduino IDE.

Thanks for the clarification Per, but I didn't regard having 2 instances of the IDE running as a problem and have not use 2.0 with anything requiring 2 separate IDE windows

Not a problem, but also not an intuitive requirement for a user who isn't "in the know". I can't think of any other applications that have different behavior depending on whether you open additional windows via a shortcut vs the application's own interface.

Thanks for all the replies. Knowing that it isn't a problem on Windows is a clue. I've subsequently dug out my ageing Mac running MacOS Sierra 10.12.6 which does allow more than one open sketch. So it seems to be a problem on my MacBook Air M1 running macOS Big Sur 11.3.1.
Are there any other mac users who would care to share their experiences? Is this a very specific bug or just a setting on my mac somewhere?