dynamic library with Qt4 dialogs in exported functions

[Onanymous]

I am trying to write a dynamic library to get access to some hardware, and use Qt for dialogs in exported functions.
Now if I try to use it from another Qt application it works more or less (more in linux, less in windows), if I omit QApplication construction, otherwise it complains. On the other hand if I try to use the library from native win application I have to include QApplication calls, and even then it works really strange. And I have not tried it yet with gtk programs. What is the proper way of doing this?