SolveSpace (https://solvespace.com), an open source CAD program crashes in certain situations when DisplayFusion is active. The developers have started to investigate and it seemed that DisplayFusion provoked some bugs in SolveSpace that they could identify. But the behavior change looks odd and might also indicate some potential bugs in DisplayFusion.
So it might be good to have a look at it from your side, too.

Here the stance of one of the SolveSpace devs after investigating the issue:

"However after looking much more carefully at he code I can fairly confidently say that DisplayFusion does something bad/buggy. Probably after injecting itself into each process - to achieve it's... windows management? functions - it makes bad Win32 calls that cause GetLastError to be non zero."

https://github.com/solvespace/solvespace/issues/817

Switching off DisplayFusion solves the program crashes. But I am quite used to the convenience DisplayFusion offers, so a fix would be really great!

P.S.: Just tried it with DisplayFusion Pro 9.7.1 Beta (upgraded from 9.6 Pro). The problem still occurs with the latest beta version.

Hi, I am not developer of SolveSpace, just somebody evaluating CAD programs for a hobby project

As far as I understand the commit, after e.g. calling IsWindowVisible or ShowWindow GetLastError returns an error when DisplayFusion is loaded and no error if it isn't.

https://github.com/solvespace/solvespace/pull/829

Disabling application hooks seems to have helped also.

Tested Beta 7, checked whether I could still reproduce the problem (yes, I could) and then updated to Beta 9. Now the problem seems to be gone. Thanks, perfect!