If you are using the main C++ distribution of wxWidgets, Feel free to ask any question related to wxWidgets development here. This means questions regarding to C++ and wxWidgets, not compile problems.
Just before I tried anything here: When I have a main application that is a plain wxWidgets application it should be no problem to use an external library that accesses wxWidgets functionality too?
Is the initialization that is done by the main applicationn (Mainloop starting and so on) enough or are there any preconditions that have to be met by the external library?