If someone still needs a solution for this -
You can simply drag the tab of one file to the side or bottom of the editor space, for example:

And the result will be:

Now you can drag, like other tabs, into a new group of tabs, and you have two separate groups of tabs (but one editor window ...). You can, of course, drag the line of the middle edge to the right end and fully work only with the first group or drag it to the left end and fully work with the second.
Pay attention to one drawback here: if the line is at one of the ends, you do not see the tabs and file names of the hidden group, and if you forget that you opened a file there and try to open it again, you will not see it open or any changes in the IDE because the control goes to an already open tab, but you donβt see it.
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