I don't know if it's a case of squeaky wheels or what (one set of users is more likely to complain than others) but I encounter "white flashes" with third party

I don't know if it's a case of squeaky wheels or what (one set of users is more likely to complain than others) but I encounter "white flashes" with third party UI toolkits like you describe considerably less often under macOS than I do under Windows. Linux sits somewhere in between.