I feel as though this is an issue with Affinity Designer that has been around for a long time - so I don’t know if it’ll get fixed anytime soon.
Just curious, why not go ahead and use actual pixel units for the export?
I guess that I was just following the Rack plugin development tutorial.
I think that I’ll just stick with modifying the files, for now at least. It’s not really much of an issue now that I have them all in this script. I might avoid the issue altogether (though I’m not sure if I can escape the main panel) and just code the graphics for all of the controls/widgets in my next plugins. 