Unwanted Flexibility in μRepRap X Axis Driver Mount

Having assembled the current V0.04 I tested the X axis using my "Bogan Calibration Slide" - a slide with a piece of wire of known diameter on it. I noticed that some "50μm" steps were smaller than others, and after hunting around nailed this down to flexing of the X Axis Driver Bracket, despite having driven a couple of long M3 screws down it. So, the Axis Motor Diver Assy has picked up a couple of pair of mounting holes to anchor that a bit more firmly:

With the aid of a 2-hole Metriccano Square Strip (and another on the bottom), the Driver Assy and the Bracket are now firmly clamped together. Only one screw in each pair, dammit, but that's what I can do at the moment until I redo the Bracket with a captive nut cavity.

This was debugged basically by shoving Metriccano and business cards into gaps until the flexing observed through the microscope went away.

Much of last evening was spent battling with Flatpak, the app packaging system used for PrusaSlicer 2.9.2 which in my opinion is a step backwards from using AppImage. Flatpak mounts itself in its own little box, and to access filesystems outside of that box you have to specify to Flatpak (not Prusaslicer) that these should be accessible.

For instance, if I want to access the /mnt directory on Linux, where you manually mount disk drives and USB storage devices in fixed locations, I needed to run:

 flatpak override --user --filesystem=/mnt

or /mnt and all the drives mounted in it just will not appear in PrusaSlicer's file manager! This is not in the install docs.

Just to be clear, this is a Flatpak problem, not I Prusa problem. Though I would encourage Prusa to reconsider their use of Flatpak because I'm hunting down a couple more bugs in it that cause problems in PrusaSlicer.