Cross compilation and string issues

Trying to keep the program I am currently working on up-to-date both on my WinXP box and on a Mac, I run into some cross-compilation pitfalls. While the project builds without warnings in vs2005, it seems that gcc on Mac has a lot to complain about.

First of all some deprecated headers apparently used by the macports VTK I'm using:

In file included from /usr/include/c++/4.0.0/backward/strstream:51,
             from
../../../../opt/local/var/macports/software/vtk-devel/5.4.0_3+boost+cocoa+darwin_9+data+doc+examples+java+py26+shared+tcl+testing+wrap/opt/local/include/vtk-5.4/vtkIOStream.h:112,
             from
../../../../opt/local/var/macports/software/vtk-devel/5.4.0_3+boost+cocoa+darwin_9+data+doc+examples+java+py26+shared+tcl+testing+wrap/opt/local/include/vtk-5.4/vtkSystemIncludes.h:40,
             from
../../../../opt/local/var/macports/software/vtk-devel/5.4.0_3+boost+cocoa+darwin_9+data+doc+examples+java+py26+shared+tcl+testing+wrap/opt/local/include/vtk-5.4/vtkIndent.h:24,
             from
../../../../opt/local/var/macports/software/vtk-devel/5.4.0_3+boost+cocoa+darwin_9+data+doc+examples+java+py26+shared+tcl+testing+wrap/opt/local/include/vtk-5.4/vtkObjectBase.h:43,
             from
../../../../opt/local/var/macports/software/vtk-devel/5.4.0_3+boost+cocoa+darwin_9+data+doc+examples+java+py26+shared+tcl+testing+wrap/opt/local/include/vtk-5.4/vtkObject.h:41,
             from
../../../../opt/local/var/macports/software/vtk-devel/5.4.0_3+boost+cocoa+darwin_9+data+doc+examples+java+py26+shared+tcl+testing+wrap/opt/local/include/vtk-5.4/vtkAlgorithm.h:32,
             from
../../../../opt/local/var/macports/software/vtk-devel/5.4.0_3+boost+cocoa+darwin_9+data+doc+examples+java+py26+shared+tcl+testing+wrap/opt/local/include/vtk-5.4/vtkPolyDataAlgorithm.h:37,
             from
../../../../opt/local/var/macports/software/vtk-devel/5.4.0_3+boost+cocoa+darwin_9+data+doc+examples+java+py26+shared+tcl+testing+wrap/opt/local/include/vtk-5.4/vtkCubeSource.h:24,
             from CamVtkView.h:14,
/usr/include/c++/4.0.0/backward/backward_warning.h:32:2: warning:
#warning This file includes at least one deprecated or antiquated
header. Please consider using one of the 32 headers found in section
17.4.1.2 of the C++ standard. Examples include substituting the 
header for the  header for C++ includes, or  instead of
the deprecated header . To disable this warning use
-Wno-deprecated.

But other warnings allowed me to spot some bug of my own producing:

CamFrame.cpp:927: warning: cannot pass objects of non-POD type 'class
wxString' through '...'; call will abort at runtime

the line was :

curImg.sprintf("%s%04u.vtk", _vtkRecPrefix, m_nFrmRead);

while what I intended to do was:

curImg.Printf(wxT("%s%04u.vtk"), _vtkRecPrefix, m_nFrmRead);

And I found a link which summarizes well wxString usage:
http://wiki.wxwidgets.org/Converting_everything_to_and_from_wxString