Made the X11 version of the gui_core work with global window objects.

--HG--
extra : convert_revision : svn%3Afdd8eb12-d10e-0410-9acb-85c331704f74/trunk%402527

dlib/gui_core/gui_core_kernel_2.h

@@ -31,7 +31,7 @@ namespace dlib
 
     namespace gui_core_kernel_2_globals
     {
-        void event_handler ();
+        class event_handler_thread;
         void trigger_user_event_threadproc (void*);
 
         // This is a forward declaration for a struct that contains any 
@@ -109,7 +109,8 @@ namespace dlib
 
     private:
 
-        friend void gui_core_kernel_2_globals::event_handler ();
+        friend class gui_core_kernel_2_globals::event_handler_thread;
+
 
         canvas (
             unsigned char* bits__,
@@ -152,7 +153,7 @@ namespace dlib
 
     class base_window
     {
-        friend void gui_core_kernel_2_globals::event_handler ();
+        friend class gui_core_kernel_2_globals::event_handler_thread;
         friend void gui_core_kernel_2_globals::trigger_user_event_threadproc (void*);
 
     public:

dlib/gui_core/gui_core_kernel_abstract.h

@@ -41,11 +41,6 @@ namespace dlib
             base_window
                 All methods for this class are thread safe.  You may call them 
                 from any thread and do not need to serialize access.
-
-        GENERAL WARNING
-            You can't make base_window objects before main() has been entered or
-            call get_from_clipboard() or put_on_clipboard() before 
-            main() has been entered.
     !*/
 
 // ----------------------------------------------------------------------------------------

dlib/test/gui/main.cpp

@@ -771,7 +771,7 @@ private:
 };
 
 
-        win w;
+win w;
 
 int main()
 {