This patch from upstream revision 10588.

--- fltk-1.3.3/src/Xutf8.h
+++ fltk-1.3.3/src/Xutf8.h
@@ -25,6 +25,7 @@
 #include <X11/Xlib.h>
 #include <X11/Xlocale.h>
 #include <X11/Xutil.h>
+#include <FL/Fl_Export.H>
 
 typedef struct {
 	int nb_font;
@@ -98,8 +99,8 @@
 	XUtf8FontStruct  *font_set,
 	unsigned int            ucs);
 
-int
-XGetUtf8FontAndGlyph(
+FL_EXPORT int
+fl_XGetUtf8FontAndGlyph(
         XUtf8FontStruct  *font_set,
         unsigned int            ucs,
         XFontStruct     **fnt,
--- fltk-1.3.3/src/gl_draw.cxx
+++ fltk-1.3.3/src/gl_draw.cxx
@@ -114,7 +114,7 @@
   for (int i = 0; i < 0x400; i++) {
     XFontStruct *font = NULL;
     unsigned short id;
-    XGetUtf8FontAndGlyph(gl_fontsize->font, ii, &font, &id);
+    fl_XGetUtf8FontAndGlyph(gl_fontsize->font, ii, &font, &id);
     if (font) glXUseXFont(font->fid, id, 1, gl_fontsize->listbase+ii);
     ii++;
    }
--- fltk-1.3.3/src/xutf8/utf8Wrap.c
+++ fltk-1.3.3/src/xutf8/utf8Wrap.c
@@ -816,10 +816,10 @@
 /**  get the X font and glyph ID of a UCS char                              **/
 /*****************************************************************************/
 int
-XGetUtf8FontAndGlyph(XUtf8FontStruct  *font_set,
-		     unsigned int     ucs,
-		     XFontStruct      **fnt,
-		     unsigned short   *id) {
+fl_XGetUtf8FontAndGlyph(XUtf8FontStruct  *font_set,
+			unsigned int     ucs,
+			XFontStruct      **fnt,
+			unsigned short   *id) {
 
   /* int             x; */
   int             *encodings; /* encodings array */
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