A long day at work today, and it's movie night in this household...
I did read through all the functions looking for a solution to the FDIM screen restore problem after my program finishes. There's a way to use a single display buffer in the library, across all exes, but you need to know the SID number to do it. That way, I can use it to save and restore the memory/display contents. Thinking that's exactly what the sat-nav exe would probably be doing, I looked at how it obtained this magic SID number and I saw...
gf_surface_sidlist(...);
First result from Google has this link:
https://bugreports.qt.io/browse/QTBUG-28576
Says the function is undocumented! It contains a complete use-case though
Thanks! (No, not to you QNX guys!)