Right having got the project converted correctly, I've done some more investigating.....
Note these are all loading the same project, after conversion.
I've ported to build / compile on Linux, on a machine running at 2560x1600, and 100% scaling, that displays the boxes OK. The Design PPI and PPI are both detected as 96.
With my windows setup of 3840x2160, scaled as 150%, Lazarus screws the form up on loadin and sets Design PPI to 96, and PPI to 144.
So I set windows to the same resolution as Linux, with 100% scaling and re-loaded, that was OK, DPPI=96, PPI=96
With Windows running at 3840x2160, but 100% scaling, again things where OK, DPPI=96, PPI=96
So it seems to be the IDE detecting the windows scaling and screwing things up, on *LOADING* the form rather than at conversion time.
Can this behavior be turned off perhaps?
Cheers.
Phill.