Not the same problem, but I have another problem.

If I have two or more files opened that have different devices selected, and click the other opened file then the device changes to the same device that the fist file uses.

In MC 3.0.0.5 I can have different files opened that have different devices selected, in 4.0.0.0 I have to manually change the device each time I switch between the files.

So I got back to MC 3.0.0.5