[XForms] fl_set_font_name() and segmentation fault error

[Max]

Dear all,

since I have update my desktop to the last xorg version (1.6.3) my xforms-
based program does not work anymore. :(

Indeed if I start it I get a plain "Segmentation fault" error with the 
following backtrace:


#0  0x00007fa6d51ab1f9 in XFindOnExtensionList () from /usr/lib/libX11.so.6
#1  0x00007fa6d51a1f86 in _XF86BigfontFreeFontMetrics () from 
/usr/lib/libX11.so.6
#2  0x00007fa6d51a206d in XFreeFont () from /usr/lib/libX11.so.6
#3  0x00007fa6d54ea3fe in fl_set_font_name () from /usr/lib/libforms.so.1
#4  0x000000000042110a in main (argc=1, argv=0x7fff870b04c8) at 
isoplot_main.c:169


The lines causing the issue are the followings

  fl_set_font_name(FL_NORMAL_STYLE,
                   "-adobe-helvetica-medium-r-normal-*-*-?-*-*-*-*-*-*");
  fl_set_font_name(FL_BOLD_STYLE,
                   "-adobe-helvetica-bold-r-normal-*-*-?-*-*-*-*-*-*");
  fl_set_font_name(FL_ITALIC_STYLE,
                   "-adobe-helvetica-medium-i-normal-*-*-?-*-*-*-*-*-*");
  fl_set_font_name(FL_BOLDITALIC_STYLE,
                   "-adobe-helvetica-bold-o-normal-*-*-?-*-*-*-*-*-*");

If I comment them, everything works, but my application does not look like I 
want :D

Am I using the function fl_set_font_name() in a wrong way, or there are known 
issues with the latest xorg's? How would you write the functions above?

Many thanks,
Max