>1. When I try to run it under VFP9 SP1 (on Win7Pro 64-bit in a VirtualBox VM) I get an error "Library file {SomeDrivePath\GKKCompare.fll} is invalid". Is this something in my environment or is GKKCompare not compatible with SP1?

I am running VFP 9 SP2. But I don't think SP1 should be a problem either. The FLL is the C library for comparing the code differences in C. Is the path you given in the message above the same path as the APP? Possibly it could not find the file?


>2. If I run it under VFP9 SP2 (on Win7Ult 64-bit on bare metal) the app starts. I select VCX on the initial choice screen. On the form I select "Class-to-Class" because I want to compare 2 classes within the same class library. Then I click on the yellow Open File button. In the dialog, clicking on an ellipsis button crashes with an error "Property GKKTOOLS is not found".

I will look into this. It should be defining this property in the main.prg file when the program starts. It keeps a MRU for you and recent paths.