For what it's worth, the workaround I described above $ rm .config/kdenliverc
basically seems to have fixed another bug. Here's what happened: $ export MESA_EXTENSION_OVERRIDE=-GL_ARB_draw_indirect ; kdenlive kdenlive->File->Open recent->(a kdenlive project) kdenlive->mute a track's audio move the mouse pointer to about 3 minutes on kdenlive's time line and click play the project starting at that point (if I recall correctlym by pressing the key board's space bar) It plays back in the preview monitor for a few seconds, then freezes. An error message *somewhat* *like* nouveau: kernel rejected pushbuf: Invalid argument nouveau: ch3: krec 0 pushes 1 bufs 1 relocs 0 nouveau: ch3: buf 00000000 0000000b 00000006 00000006 00000000 appeared on the console, and [883948.153199] nouveau 0000:01:00.0: kdenlive[16711]: multiple instances of buffer 36 on validation list [883948.153208] nouveau 0000:01:00.0: kdenlive[16711]: validate_init [883948.153210] nouveau 0000:01:00.0: kdenlive[16711]: validate: -22 appeared in dmesg. I'm happy to report a.) moving kdenlive's config file with $ mv .config/kdenliverc tmp seems to have worked around this bug too, and b.) I saved a copy of the config file. My question? Is there somethink like "lint"[1] that can check kdenliverc files for corruption? It seems to me that knowing which part of my kdenliverc is corrupted might facilitate fixing a bug or two. Thanks, Kingsley [1] Lint (software) https://en.wikipedia.org/wiki/Lint_%28software%29 -- Time is the fire in which we all burn.