-extern wxString oglColourToHex(const wxColour& colour);
-extern wxColour oglHexToColour(const wxString& hex);
-extern void oglDecToHex(unsigned int dec, char *buf);
-extern unsigned int oglHexToDec(char* buf);
+WXDLLIMPEXP_OGL wxString oglColourToHex(const wxColour& colour);
+WXDLLIMPEXP_OGL wxColour oglHexToColour(const wxString& hex);
+WXDLLIMPEXP_OGL void oglDecToHex(unsigned int dec, char *buf);
+WXDLLIMPEXP_OGL unsigned int oglHexToDec(char* buf);