Windows 10 Pro 22H2 19045.6809
If I run Sigil maximised (which I never do), minimised non-modal windows appear to be shown at the left hand end of the status line:
If I run Sigil in a smaller window (which I always do) minimised non-modal windows appear at the bottom edge of the monitor - i.e. in the same absolute positions, which for me means they are barely visible:
There is no indication as to what the minimised windows are - e.g. spellcheck, reports, etc.
If I open another EPUB, the minimised non-modal windows show data from the EPUB that was open when they were minimised. They should be closed when the EPUB they refer to is closed, rather than when Sigil is closed.
I also note the Reports function is now lightning fast
BR