Other infos:
- if performed under kvm, the same debian installation that previously was failed (see previous tests), under emulator it works correctly in all cases.
- when inkscape started on a physical machine, for each occurrence of the bug, this line appears in the journal:
kernel: nouveau 0000:04:00.0: bus: MMIO read of 00000000 FAULT at 6013d4 [ IBUS ]
- even when the bug does not occur, the first time I click to open the combo, the fonts update very slowly and the vertical scrollbar does not appear; after a few seconds the list no longer updates and I need to close the combobox and then reopen it for to see the vertical scroll bar appear and the list start updating slowly: from that moment, for all fonts (4083), it takes about 3 minutes to complete the loading of the entries.
Now the error should be stabilized and reproducible.
Good job!
Antonio