if (m_graphics_changed) NewGraphics ();
wxString sTmp, s, sPNG ;
- wxImage::AddHandler(new wxPNGHandler);
+ if ( wxImage::FindHandler(wxBITMAP_TYPE_PNG) == NULL )
+ wxImage::AddHandler(new wxPNGHandler);
// create suitable file name
sTmp.Printf ( wxT("_image%d.png"), m_sub_images);