qt app in a shared library?

Apologies if this has been asked and answered before, but I sure as heck can’t find it.

I’ve got an app written in Qt that I’m trying to convert to a shared library that can be used in multiple host applications – some Qt, some not. The library must be able to pop up its own Qt windows and everything. I’m having a devil of a time getting even a simple test app to work. I can dynamically load functions from the .so and those work, but if I try and pop up a QWindow it immediately segfaults.

Anybody done this? What do I have to do to make it work? Thanks!

Here’s the .pro, by the way:
TEMPLATE = lib
CONFIG += dll
QMAKE_CXXFLAGS = -fPIC -std=c+0x
HEADERS = ParamWindow.h
SOURCES = ParamWindow.cpp
QT += opengl