I've resolved this issue in a strange way, but will investigate the cause later.

In my App I had the following :-

- Main app (exe).
- A number of widget which are built as shared object (.so/.dll).
- A static library which is linked into the main app and shared objects (.a/.lib).

On windows and solaris, everything is fine, but on linux, this method, causes the main app to hang on exit, when cleaning up and closing the shared objects.

I got around the problem by changing the structure to :-

- Main app (exe).
- A number of widget which are built as shared object (.so/.dll).

Now rather than having a static library linked in, which contains the shared code, which is duplciated in each shared object, I include the C++ files in each individual *.pro file for each shared object. Building like this stops the hang.

This is a very strange issue, but as I said, it resolves my issue for now, and enables me to conitnue with my dev on QT4.