Windows display issue
Thank you for your interest in Maxima, and thank you for the bug report. I have closed this ticket as "won't fix" since the problem is not in Maxima itself. Please feel free to raise any new issues on the bug tracker or mailing list (https://sourceforge.net/projects/maxima/lists/maxima-discuss).
Hmm, I'm sorry to hear defsystem isn't working for ECL + Windows. Defsystem is an older system for building Lisp programs and indeed it hasn't been updated in decades to the best of my knowledge. I guess my advice is to try to solve the problems in ASDF, although I know that's easier said than done. I have a Windows system I can try it on, I will try to remember to try building with ECL in the near future.
incorrect integration
Closing this ticket as fixed. Git bisect shows it was fixed by commit 4d8e30 which was intended to fix #4257, nice to see this one got fixed too. I added the original problem as a test case in commit 50a7d7c.
Dominik, thanks for the additional example. I've copied it to a separate ticket: https://sourceforge.net/p/maxima/bugs/4620/
trigreduce incorrect result with domain = complex
limit( (sin(x)+1)/sin(x), x, inf); -> 1 and not und