Ken Rastatter's fixes to improve portability of this example:

These minor changes remove portability issues with the this example and allow
it to run on Win32. Specifically:

* The use of pthread_create() has been replaced by g_thread_create(). This
removes the dependency on the pthreads library. Since this is an example using
GTK+, g_thread_create() is available as it is a part of glibc.

* The CURLOPT_FILE option is now referred to by its "newer name"
CURLOPT_WRITEDATA.

* The use of CURLOPT_WRITEFUNCTION has been added.  As described in the docs,
this avoids the crashes when using a DLL under Win32.

* The output file has been renamed from "/tmp/test.curl" to "test.curl". It's
unlikely that there is a /tmp when in Win32 and other examples in libcurl
write their output files to the working directory.

docs/examples/curlgtk.c

@@ -17,10 +17,13 @@
 #include <curl/types.h> /* new for v7 */
 #include <curl/easy.h> /* new for v7 */
 
-#include <pthread.h>
-
 GtkWidget *Bar;
 
+size_t my_write_func(void *ptr, size_t size, size_t nmemb, FILE *stream)
+{
+  return fwrite(ptr, size, nmemb, stream);
+}
+
 size_t my_read_func(void *ptr, size_t size, size_t nmemb, FILE *stream)
 {
   return fread(ptr, size, nmemb, stream);
@@ -49,10 +52,11 @@ void *curl_thread(void *ptr)
   curl = curl_easy_init();
   if(curl)
   {
-    outfile = fopen("/tmp/test.curl", "w");
+    outfile = fopen("test.curl", "w");
 
     curl_easy_setopt(curl, CURLOPT_URL, url);
-    curl_easy_setopt(curl, CURLOPT_FILE, outfile);
+    curl_easy_setopt(curl, CURLOPT_WRITEDATA, outfile);
+    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, my_write_func);
     curl_easy_setopt(curl, CURLOPT_READFUNCTION, my_read_func);
     curl_easy_setopt(curl, CURLOPT_NOPROGRESS, FALSE);
     curl_easy_setopt(curl, CURLOPT_PROGRESSFUNCTION, my_progress_func);
@@ -64,6 +68,7 @@ void *curl_thread(void *ptr)
     /* always cleanup */
     curl_easy_cleanup(curl);
   }
+
   return NULL;
 }
 
@@ -71,7 +76,6 @@ int main(int argc, char **argv)
 {
   GtkWidget *Window, *Frame, *Frame2;
   GtkAdjustment *adj;
-  pthread_t curl_tid;
 
   /* Init thread */
   g_thread_init(NULL);
@@ -90,7 +94,9 @@ int main(int argc, char **argv)
   gtk_container_add(GTK_CONTAINER(Frame2), Bar);
   gtk_widget_show_all(Window);
 
-  pthread_create(&curl_tid, NULL, curl_thread, argv[1]);
+  if (!g_thread_create(&curl_thread, argv[1], FALSE, NULL) != 0)
+    g_warning("can't create the thread");
+
 
   gdk_threads_enter();
   gtk_main();