Hi, just out of curiosity....
I had to solve the same problem (need a long scrollable layout with many controls)... so I have a tip.
It can be still used legacy ScrolledLayout .res control.
Inside I prepared dummy Layout with default labels/buttons. To display this Layout at Creo dialog (via TK) you can use function ProUIListNamesSet (or other similar), which cause copying the dummy layout as other his instances (with .names from ProUIListNamesSet ).
This layouts (instances) then I change/build in source code. (I think, with TK is not possible to prepare all content in the UI Editor (in .res).)
So it finally works as Creo Option dialog, where are still ScrolledLayouts used.
BTW: it should be do with C++ Object Toolkit e.g. with NakedWindow - and change position of content with ScrollBar and OnMouseWheel (but we still could not leave Creo 2.0 and C TK)