[gtk+] Win32: remove the _is_win8_or_above global variable

[Paolo Borelli <pborelli src gnome org>]

commit 2e7f98a683e6868718417f15b4b1f449906bd585
Author: Paolo Borelli <pborelli gnome org>
Date:   Thu Feb 18 17:33:29 2016 +0100

    Win32: remove the _is_win8_or_above global variable

 gdk/win32/gdkglobals-win32.c |    2 --
 gdk/win32/gdkmain-win32.c    |    1 -
 gdk/win32/gdkprivate-win32.h |    2 --
 gdk/win32/gdkscreen-win32.c  |   13 ++++++++-----
 4 files changed, 8 insertions(+), 10 deletions(-)
---
diff --git a/gdk/win32/gdkglobals-win32.c b/gdk/win32/gdkglobals-win32.c
index 0c14a1e..4b325b5 100644
--- a/gdk/win32/gdkglobals-win32.c
+++ b/gdk/win32/gdkglobals-win32.c
@@ -80,5 +80,3 @@ gboolean        _ignore_destroy_clipboard = FALSE;
 
 HGLOBAL           _delayed_rendering_data = NULL;
 GHashTable       *_format_atom_table = NULL;
-
-gboolean          _is_win8_or_later = FALSE;
diff --git a/gdk/win32/gdkmain-win32.c b/gdk/win32/gdkmain-win32.c
index c66b540..a8a7650 100644
--- a/gdk/win32/gdkmain-win32.c
+++ b/gdk/win32/gdkmain-win32.c
@@ -128,7 +128,6 @@ _gdk_win32_windowing_init (void)
   _cf_url = RegisterClipboardFormat ("UniformResourceLocatorW");
   _cf_html_format = RegisterClipboardFormat ("HTML Format");
   _cf_text_html = RegisterClipboardFormat ("text/html");
-  _is_win8_or_later = g_win32_check_windows_version (6, 2, 0, G_WIN32_OS_ANY);
 
   _gdk_win32_selection_init ();
 }
diff --git a/gdk/win32/gdkprivate-win32.h b/gdk/win32/gdkprivate-win32.h
index 4d1dc01..38d5dc2 100644
--- a/gdk/win32/gdkprivate-win32.h
+++ b/gdk/win32/gdkprivate-win32.h
@@ -552,6 +552,4 @@ void _gdk_events_init (void);
 void _gdk_input_init  (GdkDisplay *display);
 void _gdk_input_wintab_init_check (GdkDeviceManager *device_manager);
 
-extern gboolean _is_win8_or_later;
-
 #endif /* __GDK_PRIVATE_WIN32_H__ */
diff --git a/gdk/win32/gdkscreen-win32.c b/gdk/win32/gdkscreen-win32.c
index ad84d41..df89182 100644
--- a/gdk/win32/gdkscreen-win32.c
+++ b/gdk/win32/gdkscreen-win32.c
@@ -30,6 +30,8 @@ struct _GdkWin32Screen
   GdkScreen parent_instance;
 
   GdkWindow *root_window;
+
+  gint always_composited : 1;
 };
 
 struct _GdkWin32ScreenClass
@@ -65,6 +67,9 @@ gdk_win32_screen_init (GdkWin32Screen *win32_screen)
 
   if (logpixelsx > 0)
     _gdk_screen_set_resolution (screen, logpixelsx);
+
+  /* On Windows 8 and later, DWM (composition) is always enabled */
+  win32_screen->always_composited = g_win32_check_windows_version (6, 2, 0, G_WIN32_OS_ANY);
 }
 
 void
@@ -245,14 +250,12 @@ gdk_win32_screen_get_window_stack (GdkScreen *screen)
 static gboolean
 gdk_win32_screen_is_composited (GdkScreen *screen)
 {
-  gboolean is_composited;
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), FALSE);
-
-  /* On Windows 8 and later, DWM (composition) is always enabled */
-  if (_is_win8_or_later)
+  if (GDK_WIN32_SCREEN (screen)->always_composited)
     return TRUE;
   else
     {
+      gboolean is_composited;
+
       if (DwmIsCompositionEnabled (&is_composited) != S_OK)
         return FALSE;
       return is_composited;