Crash in setVisible() of main window
Hello, forgive me that I repeat, i want that more people saw my thread and and maybe some one will help me:
Hi, welcome to devnet.
It's next to impossible to say what's wrong without some code. The best would be minimal reproducible example. Give as much information as you can and someone here will surely help you figure out what's wrong. If it happens in two different places for random users then it's most likely access to uninitialized/deleted pointer or writing out of bounds of some container/buffer. Give it a go with some static analysis tool like cppcheck and memory leak detector like vld.
I also think there's little chance that Qt has problems with showing windows. It would break a lot of software out there ;) That's most likely not a bug in Qt but in your code. You shouldn't report it on https://bugreports.qt-project.org unless you're pretty much sure it's Qt bug and you can prove it. For problems with using Qt you've got this forum and also mailing lists.