Yes, the Q button is another PITA. 1. I don't need it but it cannot be deactivated or reprogrammed for another function and 2. it is enabled much too easily by accident due it's too prominent position
In addition to reprogramming various function buttons, I still have the Q button problem. Plus, I keep inadvertently changing either the ISO or shutter speed in manual by bumping the dials.
My solution is to make the (unmarked) function button above the Q button my Lock/Unlock button. I have set up "Selected" locks on various things I don't want to change by accident, and turn on or off the selected lock using that function button.
It's a giant waste of both a function button and my time, especially when I do want to make a minor change and have to turn it off, make the change, and remember to turn Lock back on.
As I've said before, if Fujifilm wanted to implement the modern button/dial interface, they should have just paid Canon to use the 1Dx user interface. Marked buttons, everything falls into place under the fingers, easy navigation on the LCD screens, and a physical Lock switch that can be configured to lock everything.
I'm not sure who Fujifilm hired to design the UI for the GFX-100, but it appears that they didn't talk to photographers about it.