I've turned off Bluetooth on my Thinkpad and replaced my Bluetooth keyboard and mouse with wireless USB units: a cheap Logitech K360 compact keyboard and M325 mouse. After 3 days there is no sign of the memory leaks that I wrote about on Sunday. The clue that Bluetooth, or these particular devices, might be implicated was the presence of a gsd-wacom process at the top of top's memory-sorted table. I've no Wacom device, but I associate them with Bluetooth. Removing Bluetooth devices from my workplace hasn't fixed the bug in Gnome or the device driver, but the bug is now dormant. I'm moving on.