[gtk+/xi2] Add gdk_enable_multidevice().

[Carlos Garnacho <carlosg src gnome org>]

commit c66aabedac50847e33a3dcfc52d6d904e43ff86c
Author: Carlos Garnacho <carlos gnome org>
Date:   Sat Jan 9 15:36:24 2010 +0100

    Add gdk_enable_multidevice().
    
    This is a global switch to enable multidevice awareness. In the X11 backend,
    if this function is called, XInput2 will be used to handle events if available,
    else either XInput1 and/or core events will be used.

 gdk/gdk.c                      |   16 ++++++++++++++++
 gdk/gdk.h                      |    1 +
 gdk/gdkglobals.c               |    1 +
 gdk/gdkinternals.h             |    1 +
 gdk/x11/gdkdevicemanager-x11.c |    5 +++--
 5 files changed, 22 insertions(+), 2 deletions(-)
---
diff --git a/gdk/gdk.c b/gdk/gdk.c
index 5dd2fae..dc8e207 100644
--- a/gdk/gdk.c
+++ b/gdk/gdk.c
@@ -806,5 +806,21 @@ gdk_set_program_class (const char *program_class)
   gdk_progclass = g_strdup (program_class);
 }
 
+/**
+ * gdk_enable_multidevice:
+ *
+ * Enables multidevice support in GDK. Note that individual
+ * #GdkWindow<!-- -->s still need to explicitly enable multidevice
+ * awareness through gdk_window_set_support_multidevice().
+ **/
+void
+gdk_enable_multidevice (void)
+{
+  if (gdk_initialized)
+    return;
+
+  _gdk_enable_multidevice = TRUE;
+}
+
 #define __GDK_C__
 #include "gdkaliasdef.c"
diff --git a/gdk/gdk.h b/gdk/gdk.h
index dff03c1..d24ee13 100644
--- a/gdk/gdk.h
+++ b/gdk/gdk.h
@@ -68,6 +68,7 @@ G_BEGIN_DECLS
 /* Initialization, exit and events
  */
 #define	  GDK_PRIORITY_EVENTS		(G_PRIORITY_DEFAULT)
+void      gdk_enable_multidevice        (void);
 void 	  gdk_parse_args	   	(gint	   	*argc,
 					 gchar        ***argv);
 void 	  gdk_init		   	(gint	   	*argc,
diff --git a/gdk/gdkglobals.c b/gdk/gdkglobals.c
index 4c3ad80..a805bcc 100644
--- a/gdk/gdkglobals.c
+++ b/gdk/gdkglobals.c
@@ -40,6 +40,7 @@ gchar              *_gdk_display_name = NULL;
 gint                _gdk_screen_number = -1;
 gchar              *_gdk_display_arg_name = NULL;
 gboolean            _gdk_native_windows = FALSE;
+gboolean            _gdk_enable_multidevice = FALSE;
 
 GSList             *_gdk_displays = NULL;
 
diff --git a/gdk/gdkinternals.h b/gdk/gdkinternals.h
index 69e4c26..32cc15b 100644
--- a/gdk/gdkinternals.h
+++ b/gdk/gdkinternals.h
@@ -297,6 +297,7 @@ extern GSList    *_gdk_displays;
 extern gchar     *_gdk_display_name;
 extern gint       _gdk_screen_number;
 extern gchar     *_gdk_display_arg_name;
+extern gboolean   _gdk_enable_multidevice;
 
 void      _gdk_events_queue  (GdkDisplay *display);
 GdkEvent* _gdk_event_unqueue (GdkDisplay *display);
diff --git a/gdk/x11/gdkdevicemanager-x11.c b/gdk/x11/gdkdevicemanager-x11.c
index 5d04842..335764b 100644
--- a/gdk/x11/gdkdevicemanager-x11.c
+++ b/gdk/x11/gdkdevicemanager-x11.c
@@ -31,7 +31,7 @@
 GdkDeviceManager *
 _gdk_device_manager_new (GdkDisplay *display)
 {
-  if (G_UNLIKELY (!g_getenv ("GDK_CORE_DEVICE_EVENTS")))
+  if (!g_getenv ("GDK_CORE_DEVICE_EVENTS"))
     {
 #if defined (XINPUT_2) || defined (XINPUT_XFREE)
       int opcode, firstevent, firsterror;
@@ -48,7 +48,8 @@ _gdk_device_manager_new (GdkDisplay *display)
           major = 2;
           minor = 0;
 
-          if (XIQueryVersion (xdisplay, &major, &minor) != BadRequest)
+          if (_gdk_enable_multidevice &&
+              XIQueryVersion (xdisplay, &major, &minor) != BadRequest)
             {
               GdkDeviceManagerXI2 *device_manager_xi2;