Using 0.991-18, if I open many files (say 20ish) from one book, then click quickly on the close tab red "x" without moving the mouse to close the files, Sigil crashes. This happens for one particular book and is repeatable, but doesn't happen on a couple of other books I tried. This particular book is copyright, so I can't post it here.
I can see a compile time debug option at
https://github.com/Sigil-Ebook/Sigil...o/DEBUGGING.md. Is there anything I can do to provide debug output from a standard build, or anything else to help track down where the crash is?