X11 platform: use Gnome printer dialog when the GTK library is available at run-time

The code to determine whether the GTK library is available is now in Fl_X11_System_Driver::probe_for_GTK()
called both by Fl_Printer::begin_job() and Fl_Native_File_Chooser.
New Fl::option OPTION_PRINTER_USES_GTK allows to deactivate use of
the Gnome print dialog.

Minor change in Fl_Native_File_Chooser: GTK version 3 is searched before version 2,
whereas the search order was the opposite before.

5 files changed, 261 insertions, 60 deletions

diff --git a/src/Fl.cxx b/src/Fl.cxx
index 1327509e8..0a4e22ee9 100644
--- a/src/Fl.cxx
+++ b/src/Fl.cxx
@@ -1866,7 +1866,9 @@ bool Fl::option(Fl_Option opt)
       options_[OPTION_SHOW_TOOLTIPS] = tmp;
       opt_prefs.get("FNFCUsesGTK", tmp, 1);                     // default: on
       options_[OPTION_FNFC_USES_GTK] = tmp;
-      
+      opt_prefs.get("PrintUsesGTK", tmp, 1);                     // default: on
+      options_[OPTION_PRINTER_USES_GTK] = tmp;
+
       opt_prefs.get("ShowZoomFactor", tmp, 1);                  // default: on
       options_[OPTION_SHOW_SCALING] = tmp;
     }
@@ -1888,7 +1890,9 @@ bool Fl::option(Fl_Option opt)
       if (tmp >= 0) options_[OPTION_SHOW_TOOLTIPS] = tmp;
       opt_prefs.get("FNFCUsesGTK", tmp, -1);
       if (tmp >= 0) options_[OPTION_FNFC_USES_GTK] = tmp;
-      
+      opt_prefs.get("PrintUsesGTK", tmp, -1);
+      if (tmp >= 0) options_[OPTION_PRINTER_USES_GTK] = tmp;
+
       opt_prefs.get("ShowZoomFactor", tmp, -1);
       if (tmp >= 0) options_[OPTION_SHOW_SCALING] = tmp;
     }
diff --git a/src/Fl_Native_File_Chooser_GTK.cxx b/src/Fl_Native_File_Chooser_GTK.cxx
index 2d6b819f9..575ab4c70 100644
--- a/src/Fl_Native_File_Chooser_GTK.cxx
+++ b/src/Fl_Native_File_Chooser_GTK.cxx
@@ -24,6 +24,7 @@
 
 #if HAVE_DLSYM && HAVE_DLFCN_H
 #include <dlfcn.h>   // for dlopen et al
+#include "drivers/X11/Fl_X11_System_Driver.H"
 #endif
 #include <locale.h>  // for setlocale
 
@@ -159,10 +160,6 @@ static XX_g_slist_length fl_g_slist_length = NULL;
 typedef void (*XX_g_slist_free) (GSList *);
 static XX_g_slist_free fl_g_slist_free = NULL;
 
-// gboolean gtk_init_check (int *argc, char ***argv);
-typedef gboolean (*XX_gtk_init_check)(int *, char ***);
-static XX_gtk_init_check fl_gtk_init_check = NULL;
-
 // void gtk_widget_destroy (GtkWidget *widget);
 typedef void (*XX_gtk_widget_destroy) (GtkWidget *);
 static XX_gtk_widget_destroy fl_gtk_widget_destroy = NULL;
@@ -262,9 +259,9 @@ static XX_gtk_widget_show_now fl_gtk_widget_show_now = NULL;
 typedef GdkWindow* (*XX_gtk_widget_get_window)(GtkWidget *);
 static XX_gtk_widget_get_window fl_gtk_widget_get_window = NULL;
 
-// Window gdk_x11_drawable_get_xid(GdkWindow *);
-typedef Window (*XX_gdk_x11_drawable_get_xid)(GdkWindow *);
-static XX_gdk_x11_drawable_get_xid fl_gdk_x11_drawable_get_xid = NULL;
+// Window gdk_x11_drawable_get_xid(GdkWindow *); or gdk_x11_window_get_xid
+typedef Window (*gdk_to_X11_t)(GdkWindow*);
+static gdk_to_X11_t fl_gdk_to_X11 = NULL;
 
 // GtkWidget *gtk_check_button_new_with_label(const gchar *);
 typedef GtkWidget* (*XX_gtk_check_button_new_with_label)(const gchar *);
@@ -492,15 +489,8 @@ static void run_response_handler(GtkDialog *dialog, gint response_id, gpointer d
 int Fl_GTK_Native_File_Chooser_Driver::fl_gtk_chooser_wrapper()
 {
   int result = 1;
-  static int have_gtk_init = 0;
   char *p;
-  
-  if(!have_gtk_init) {
-    have_gtk_init = -1;
-    int ac = 0;
-    fl_gtk_init_check(&ac, NULL);
-  }
-  
+
   if(gtkw_ptr) { // discard the previous dialog widget
     fl_gtk_widget_destroy (gtkw_ptr);
     gtkw_ptr = NULL;
@@ -611,7 +601,7 @@ int Fl_GTK_Native_File_Chooser_Driver::fl_gtk_chooser_wrapper()
   fl_gtk_widget_show_now(gtkw_ptr); // map the GTK window on screen
   if (firstw) {
     GdkWindow* gdkw = fl_gtk_widget_get_window(gtkw_ptr);
-    Window xw = fl_gdk_x11_drawable_get_xid(gdkw); // get the X11 ref of the GTK window
+    Window xw = fl_gdk_to_X11(gdkw); // get the X11 ref of the GTK window
     XSetTransientForHint(fl_display, xw, fl_xid(firstw)); // set the GTK window transient for the last FLTK win
     }
   gboolean state = fl_gtk_file_chooser_get_show_hidden((GtkFileChooser *)gtkw_ptr);
@@ -701,57 +691,22 @@ fprintf(stderr, "%s\n", pc_dl_error);       \
 did_find_GTK_libs = 0;                      \
 return; }
 
-static void* fl_dlopen(const char *filename1, const char *filename2)
-{
-  void *ptr = dlopen(filename1, RTLD_LAZY | RTLD_GLOBAL);
-  if (!ptr) ptr = dlopen(filename2, RTLD_LAZY | RTLD_GLOBAL);
-  return ptr;
-}
+
 #endif // HAVE_DLSYM && HAVE_DLFCN_H
 
-/* 
+/*
  * Use dlopen to see if we can load the gtk dynamic libraries that
  * will allow us to create a GtkFileChooserDialog() on the fly,
  * without linking to the GTK libs at compile time.
  */
 void Fl_GTK_Native_File_Chooser_Driver::probe_for_GTK_libs(void) {
 #if HAVE_DLSYM && HAVE_DLFCN_H
-  void *ptr_glib    = NULL;
-  void *ptr_gtk     = NULL;
-  
-#   ifdef __APPLE_CC__ // allows testing on Darwin + X11
-  ptr_glib    = dlopen("/sw/lib/libglib-2.0.dylib", RTLD_LAZY | RTLD_GLOBAL);
-#   else
-  ptr_glib    = fl_dlopen("libglib-2.0.so", "libglib-2.0.so.0");
-#   endif
-  // Try first with GTK2
-#   ifdef __APPLE_CC__ // allows testing on Darwin + X11
-  ptr_gtk     = dlopen("/sw/lib/libgtk-x11-2.0.dylib", RTLD_LAZY | RTLD_GLOBAL);
-#else
-  ptr_gtk     = fl_dlopen("libgtk-x11-2.0.so", "libgtk-x11-2.0.so.0");
-#endif
-  if (ptr_gtk && ptr_glib) {
-#ifdef DEBUG
-    puts("selected GTK-2\n");
-#endif
-  }
-  else {// Try then with GTK3
-    ptr_gtk     = fl_dlopen("libgtk-3.so", "libgtk-3.so.0");
-#ifdef DEBUG
-    if (ptr_gtk && ptr_glib) {
-      puts("selected GTK-3\n");
-    }
-#endif
-  }
-  
-  if((!ptr_glib) || (!ptr_gtk)) {
-#ifdef DEBUG
-    puts("Failure to load libglib or libgtk");
-#endif
+  void  *ptr_gtk;
+  if ( !Fl_X11_System_Driver::probe_for_GTK(2, 4, &ptr_gtk)) {
     did_find_GTK_libs = 0;
     return;
   }
-  
+  void *ptr_glib = ptr_gtk;
   char *pc_dl_error; // used to report errors by the GET_SYM macro...
   // items we need from GLib
   GET_SYM(g_free, ptr_glib);
@@ -759,7 +714,6 @@ void Fl_GTK_Native_File_Chooser_Driver::probe_for_GTK_libs(void) {
   GET_SYM(g_slist_length, ptr_glib);
   GET_SYM(g_slist_free, ptr_glib);
   // items we need from GTK
-  GET_SYM(gtk_init_check, ptr_gtk);
   GET_SYM(gtk_widget_destroy, ptr_gtk);
   GET_SYM(gtk_file_chooser_set_select_multiple, ptr_gtk);
   GET_SYM(gtk_file_chooser_set_do_overwrite_confirmation, ptr_gtk);
@@ -784,7 +738,9 @@ void Fl_GTK_Native_File_Chooser_Driver::probe_for_GTK_libs(void) {
   GET_SYM(gtk_file_chooser_set_extra_widget, ptr_gtk);
   GET_SYM(gtk_widget_show_now, ptr_gtk);
   GET_SYM(gtk_widget_get_window, ptr_gtk);
-  GET_SYM(gdk_x11_drawable_get_xid, ptr_gtk);
+  fl_gdk_to_X11 = (gdk_to_X11_t)dlsym(ptr_gtk, "gdk_x11_drawable_get_xid");
+  if (!fl_gdk_to_X11) fl_gdk_to_X11 = (gdk_to_X11_t)dlsym(ptr_gtk, "gdk_x11_window_get_xid");
+  if (!fl_gdk_to_X11) { did_find_GTK_libs = 0; return; }
   GET_SYM(gtk_check_button_new_with_label, ptr_gtk);
   GET_SYM(g_signal_connect_data, ptr_gtk);
   GET_SYM(gtk_toggle_button_get_active, ptr_gtk);
diff --git a/src/drivers/Posix/Fl_Posix_Printer_Driver.cxx b/src/drivers/Posix/Fl_Posix_Printer_Driver.cxx
index 835529be1..926f1b3d6 100644
--- a/src/drivers/Posix/Fl_Posix_Printer_Driver.cxx
+++ b/src/drivers/Posix/Fl_Posix_Printer_Driver.cxx
@@ -31,8 +31,188 @@ class Fl_Posix_Printer_Driver : public Fl_PostScript_File_Device {
   virtual int begin_job(int pagecount, int *frompage = NULL, int *topage = NULL);
 };
 
+#if HAVE_DLSYM && HAVE_DLFCN_H
+// GTK types
+#include <dlfcn.h>   // for dlopen et al
+#include <unistd.h>  // for mkstemp
+#include <FL/filename.H>
+#include "../X11/Fl_X11_System_Driver.H"
+#define GTK_PAPER_NAME_LETTER "na_letter"
+#define GTK_RESPONSE_NONE 0
+#define GTK_RESPONSE_OK -5
+#define GTK_PRINT_PAGES_RANGES 2
+class Fl_GTK_Printer_Driver : public Fl_PostScript_File_Device {
+public:
+  typedef int gboolean;
+  typedef struct _GtkPrintUnixDialog GtkPrintUnixDialog;
+  typedef struct _GtkDialog GtkDialog;
+  typedef struct _GtkPrintSettings GtkPrintSettings;
+  typedef struct _GtkPageSetup GtkPageSetup;
+  enum GtkPageOrientation {GTK_PAGE_ORIENTATION_PORTRAIT, GTK_PAGE_ORIENTATION_LANDSCAPE};
+  typedef struct _GtkPaperSize GtkPaperSize;
+  typedef struct _GtkPrinter GtkPrinter;
+  typedef struct _GtkPrintJob GtkPrintJob;
+  typedef struct _GtkWidget GtkWidget;
+  struct GError;
+  
+  GtkPrintJob *pjob; // data shared between begin_job() and end_job()
+  char tmpfilename[50]; // name of temporary PostScript file containing to-be-printed data
+  virtual int begin_job(int pagecount, int *frompage = NULL, int *topage = NULL);
+  virtual void end_job();
+  static bool probe_for_GTK();
+  static void *ptr_gtk; // points to the GTK dynamic lib or NULL
+  
+  typedef GtkPrintUnixDialog* (*gtk_print_unix_dialog_new_t)(const char*, void*);
+  typedef int (*gtk_dialog_run_t)(GtkDialog*);
+  typedef GtkPrintSettings *(*gtk_print_unix_dialog_get_settings_t)(GtkPrintUnixDialog*);
+  typedef void (*gtk_print_unix_dialog_set_settings_t)(GtkPrintUnixDialog*, GtkPrintSettings*);
+  typedef GtkPageSetup *(*gtk_print_unix_dialog_get_page_setup_t)(GtkPrintUnixDialog*);
+  typedef GtkPageOrientation (*gtk_page_setup_get_orientation_t)(GtkPageSetup*);
+  typedef GtkPaperSize* (*gtk_page_setup_get_paper_size_t)(GtkPageSetup*);
+  typedef const char * (*gtk_paper_size_get_name_t)(GtkPaperSize*);
+  typedef GtkPrinter * (*gtk_print_unix_dialog_get_selected_printer_t)(GtkPrintUnixDialog*);
+  typedef int (*gtk_printer_accepts_ps_t)(GtkPrinter*);
+  typedef int (*gtk_printer_is_active_t)(GtkPrinter*);
+  typedef GtkPrintJob *(*gtk_print_job_new_t)(const char *, GtkPrinter *, GtkPrintSettings *, GtkPageSetup *);
+  typedef void (*gtk_widget_hide_t)(GtkWidget*);
+  typedef void (*gtk_widget_destroy_t)(GtkWidget*);
+  typedef gboolean (*gtk_events_pending_t)(void);
+  typedef void (*gtk_main_iteration_t)(void);
+  typedef int (*gtk_print_job_set_source_file_t)(GtkPrintJob *job, const char *filename, GError **error);
+  typedef void (*gtk_print_job_send_t)(GtkPrintJob *, void* , gboolean* , void* );
+  typedef void (*gtk_print_settings_set_t) (GtkPrintSettings *settings, const char *key, const char *value);
+  typedef const char * (*gtk_print_settings_get_t) (GtkPrintSettings *settings, const char *key );
+  typedef int (*gtk_print_settings_get_print_pages_t)(GtkPrintSettings*);
+  struct GtkPageRange { int start, end; };
+  typedef GtkPageRange* (*gtk_print_settings_get_page_ranges_t)(GtkPrintSettings*, int*);
+  typedef void (*g_object_unref_t)(void* object);
+};
+
+// the CALL_GTK macro produces the source code to call a GTK function given its name
+// or to get a pointer to this function :
+// CALL_GTK(gtk_my_function) produces ((gtk_my_function_t)dlsym(ptr_gtk, "gtk_my_function"))
+#define CALL_GTK(NAME) ((NAME##_t)dlsym(ptr_gtk, #NAME))
+
+void *Fl_GTK_Printer_Driver::ptr_gtk = NULL;
+
+// test wether GTK is available at run-time
+bool Fl_GTK_Printer_Driver::probe_for_GTK() {
+  return Fl_X11_System_Driver::probe_for_GTK(2, 10, &ptr_gtk);
+}
+
+
+int Fl_GTK_Printer_Driver::begin_job(int pagecount, int *firstpage, int *lastpage) {
+  enum Fl_Paged_Device::Page_Format format = Fl_Paged_Device::A4;
+  enum Fl_Paged_Device::Page_Layout layout = Fl_Paged_Device::PORTRAIT ;
+  
+  GtkPrintUnixDialog *pdialog = CALL_GTK(gtk_print_unix_dialog_new)(Fl_Printer::dialog_title, NULL); //2.10
+  GtkPrintSettings *psettings = CALL_GTK(gtk_print_unix_dialog_get_settings)(pdialog); //2.10
+  CALL_GTK(gtk_print_settings_set)(psettings, "output-file-format", "ps"); //2.10
+  char line[FL_PATH_MAX + 20], cwd[FL_PATH_MAX];
+  sprintf(line, "file://%s/FLTK.ps", fl_getcwd(cwd, FL_PATH_MAX));
+  CALL_GTK(gtk_print_settings_set)(psettings, "output-uri", line); //2.10
+  CALL_GTK(gtk_print_unix_dialog_set_settings)(pdialog, psettings); //2.10
+  CALL_GTK(g_object_unref)(psettings);
+  int response_id = CALL_GTK(gtk_dialog_run)((GtkDialog*)pdialog);
+  if (response_id == GTK_RESPONSE_OK) {
+    GtkPageSetup *psetup = CALL_GTK(gtk_print_unix_dialog_get_page_setup)(pdialog); //2.10
+    GtkPageOrientation orient = CALL_GTK(gtk_page_setup_get_orientation)(psetup); //2.10
+    if (orient == GTK_PAGE_ORIENTATION_LANDSCAPE) layout = Fl_Paged_Device::LANDSCAPE;
+    GtkPaperSize* psize = CALL_GTK(gtk_page_setup_get_paper_size)(psetup); //2.10
+    const char *pname = CALL_GTK(gtk_paper_size_get_name)(psize); //2.10
+    if (strcmp(pname, GTK_PAPER_NAME_LETTER) == 0) format = Fl_Paged_Device::LETTER;
+    GtkPrinter *gprinter = CALL_GTK(gtk_print_unix_dialog_get_selected_printer)(pdialog); //2.10
+    psettings = CALL_GTK(gtk_print_unix_dialog_get_settings)(pdialog); //2.10
+    const char* p = CALL_GTK(gtk_print_settings_get)(psettings, "output-uri"); //2.10
+    bool printing_to_file = (p != NULL);
+    if (printing_to_file) {
+      p += 6; // skip "file://" prefix
+      strcpy(line, p);
+      int l = strlen(p);
+      if (strcmp(p+l-4, "/.ps") == 0) {
+        line[l-3] = 0;
+        strcat(line, "FLTK.ps");
+      }
+    }
+    if (firstpage && lastpage) {
+      *firstpage = 1; *lastpage = pagecount;
+      if (CALL_GTK(gtk_print_settings_get_print_pages)(psettings) == GTK_PRINT_PAGES_RANGES) { // 2.10
+        int num_ranges;
+        GtkPageRange *ranges = CALL_GTK(gtk_print_settings_get_page_ranges)(psettings, &num_ranges); //2.10
+        if (num_ranges > 0) {
+          *firstpage = ranges[0].start + 1;
+          *lastpage = ranges[0].end + 1;
+          free(ranges);
+        }
+      }
+    }
+    response_id = GTK_RESPONSE_NONE;
+    if (printing_to_file) {
+      pjob = NULL;
+      FILE *output = fopen(line, "w");
+      if (output) {
+        Fl_PostScript_File_Device::begin_job(output, 0, format, layout);
+        response_id = GTK_RESPONSE_OK;
+      }
+    } else if ( CALL_GTK(gtk_printer_accepts_ps)(gprinter) && //2.10
+        CALL_GTK(gtk_printer_is_active)(gprinter) ) { // 2.10
+      strcpy(tmpfilename, "/tmp/FLTKprintjobXXXXXX");
+      int fd = mkstemp(tmpfilename);
+      if (fd >= 0) {
+        FILE *output = fdopen(fd, "w");
+        Fl_PostScript_File_Device::begin_job(output, 0, format, layout);
+        pjob = CALL_GTK(gtk_print_job_new)("FLTK print job", gprinter, psettings, psetup); //2.10
+        response_id = GTK_RESPONSE_OK;
+      }
+    }
+    CALL_GTK(g_object_unref)(psettings);
+  }
+  CALL_GTK(gtk_widget_hide)((GtkWidget*)pdialog);
+  gtk_events_pending_t fl_gtk_events_pending = CALL_GTK(gtk_events_pending);
+  gtk_main_iteration_t fl_gtk_main_iteration = CALL_GTK(gtk_main_iteration);
+  while (fl_gtk_events_pending()) fl_gtk_main_iteration();
+  CALL_GTK(gtk_widget_destroy)((GtkWidget*)pdialog);
+  Fl_Window *first = Fl::first_window();
+  if (first) {
+    Fl_Surface_Device::push_current(Fl_Display_Device::display_device());
+    first->show();
+    while (Fl::ready()) Fl::check();
+    Fl_Surface_Device::pop_current();
+  }
+  return (response_id == GTK_RESPONSE_OK ? 0 : 1);
+}
+
+static void pJobCompleteFunc(Fl_GTK_Printer_Driver::GtkPrintJob *print_job, Fl_GTK_Printer_Driver::gboolean *user_data, const Fl_GTK_Printer_Driver::GError *error) {
+  *user_data = true;
+}
+static void pDestroyNotify(void* data) {}
+
+void Fl_GTK_Printer_Driver::end_job() {
+  Fl_PostScript_File_Device::end_job();
+  Fl_PostScript_Graphics_Driver *psgd = driver();
+  fclose(psgd->output);
+  if (!pjob) return;
+  GError *gerr;
+  gboolean gb = CALL_GTK(gtk_print_job_set_source_file)(pjob, tmpfilename, &gerr); //2.10
+  if (gb) {
+    gb = false;
+    CALL_GTK(gtk_print_job_send)(pjob, (void*)pJobCompleteFunc, &gb, (void*)pDestroyNotify); //2.10
+    gtk_main_iteration_t fl_gtk_main_iteration = CALL_GTK(gtk_main_iteration);
+    while (!gb) {
+      fl_gtk_main_iteration();
+    }
+  }
+  fl_unlink(tmpfilename);
+}
+#endif // HAVE_DLSYM && HAVE_DLFCN_H
+
+
 Fl_Paged_Device* Fl_Printer::newPrinterDriver(void)
 {
+#if HAVE_DLSYM && HAVE_DLFCN_H
+  static bool gtk = ( Fl::option(Fl::OPTION_PRINTER_USES_GTK) ? Fl_GTK_Printer_Driver::probe_for_GTK() : false);
+  if (gtk) return new Fl_GTK_Printer_Driver();
+#endif
   return new Fl_Posix_Printer_Driver();
 }
 
diff --git a/src/drivers/X11/Fl_X11_System_Driver.H b/src/drivers/X11/Fl_X11_System_Driver.H
index b7d6e9ff7..138959d75 100644
--- a/src/drivers/X11/Fl_X11_System_Driver.H
+++ b/src/drivers/X11/Fl_X11_System_Driver.H
@@ -20,6 +20,7 @@
 #ifndef FL_X11_SYSTEM_DRIVER_H
 #define FL_X11_SYSTEM_DRIVER_H
 
+#include "../../config_lib.h"
 #include "../Posix/Fl_Posix_System_Driver.H"
 
 class Fl_X11_System_Driver : public Fl_Posix_System_Driver {
@@ -63,6 +64,9 @@ public:
   virtual void add_fd(int fd, Fl_FD_Handler cb, void* = 0);
   virtual void remove_fd(int, int when);
   virtual void remove_fd(int);
+#if HAVE_DLSYM && HAVE_DLFCN_H
+  static bool probe_for_GTK(int major, int minor, void **ptr_gtk);
+#endif
 };
 
 #endif /* FL_X11_SYSTEM_DRIVER_H */
diff --git a/src/drivers/X11/Fl_X11_System_Driver.cxx b/src/drivers/X11/Fl_X11_System_Driver.cxx
index 42d403299..f406dce02 100644
--- a/src/drivers/X11/Fl_X11_System_Driver.cxx
+++ b/src/drivers/X11/Fl_X11_System_Driver.cxx
@@ -517,6 +517,63 @@ int Fl_X11_System_Driver::utf8locale() {
   return ret;
 }
 
+#if HAVE_DLSYM && HAVE_DLFCN_H
+#include <dlfcn.h>   // for dlopen et al
+
+static void* fl_dlopen(const char *filename1, const char *filename2)
+{
+  void *ptr = dlopen(filename1, RTLD_LAZY | RTLD_GLOBAL);
+  if (!ptr) ptr = dlopen(filename2, RTLD_LAZY | RTLD_GLOBAL);
+  return ptr;
+}
+
+bool Fl_X11_System_Driver::probe_for_GTK(int major, int minor, void **ptr_gtk) {
+  typedef void (*init_t)(int*, void*);
+  *ptr_gtk = NULL;
+  // was GTK previously loaded?
+  init_t init_f = (init_t)dlsym(RTLD_DEFAULT, "gtk_init_check");
+  if (init_f) { // yes it was.
+    *ptr_gtk = RTLD_DEFAULT; // Caution: NULL under linux, not-NULL under Darwin
+  } else {
+    // Try first with GTK3
+    *ptr_gtk     = fl_dlopen("libgtk-3.so", "libgtk-3.so.0");
+    if (*ptr_gtk) {
+#ifdef DEBUG
+      puts("selected GTK-3\n");
+#endif
+    } else {
+      // Try then with GTK2
+#   ifdef __APPLE_CC__ // allows testing on Darwin + X11
+      *ptr_gtk     = ::dlopen("/sw/lib/libgtk-x11-2.0.dylib", RTLD_LAZY | RTLD_GLOBAL);
+#else
+      *ptr_gtk     = fl_dlopen("libgtk-x11-2.0.so", "libgtk-x11-2.0.so.0");
+#endif
+    }
+    if (*ptr_gtk) {
+#ifdef DEBUG
+      puts("selected GTK-2\n");
+#endif
+    } else {
+#ifdef DEBUG
+      puts("Failure to load libgtk");
+#endif
+      return false;
+    }
+    init_f = (init_t)dlsym(*ptr_gtk, "gtk_init_check");
+    if (!init_f) return false;
+  }
+  int ac = 0;
+  init_f(&ac, NULL);
+  // now check if running version is high enough
+  if (dlsym(*ptr_gtk, "gtk_get_major_version") == NULL) { // YES indicates V 3
+    typedef const char* (*check_t)(int, int, int);
+    check_t check_f = (check_t)dlsym(*ptr_gtk, "gtk_check_version");
+    if (!check_f || check_f(major, minor, 0) ) return false;
+  }
+  return true;
+}
+#endif // HAVE_DLSYM && HAVE_DLFCN_H
+
 #if !defined(FL_DOXYGEN)
 
 const char *Fl_X11_System_Driver::shortcut_add_key_name(unsigned key, char *p, char *buf, const char **eom)