GdkScreen: fix precondition checks in the public API

Move g_return_if_fail() stuff from the backends to the public
functions in gdkscreen.c itself, and some fixes for ugly formatting in
the various gdkscreen-backend.c files.

6 files changed, 99 insertions, 156 deletions

diff --git a/gdk/broadway/gdkscreen-broadway.c b/gdk/broadway/gdkscreen-broadway.c
index 899ba9f729..f970be91e1 100644
--- a/gdk/broadway/gdkscreen-broadway.c
+++ b/gdk/broadway/gdkscreen-broadway.c
@@ -34,8 +34,8 @@
 #include <stdlib.h>
 #include <string.h>
 
-static void         gdk_broadway_screen_dispose     (GObject		  *object);
-static void         gdk_broadway_screen_finalize    (GObject		  *object);
+static void   gdk_broadway_screen_dispose     (GObject *object);
+static void   gdk_broadway_screen_finalize    (GObject *object);
 
 G_DEFINE_TYPE (GdkBroadwayScreen, gdk_broadway_screen, GDK_TYPE_SCREEN)
 
@@ -49,61 +49,48 @@ gdk_broadway_screen_init (GdkBroadwayScreen *screen)
 static GdkDisplay *
 gdk_broadway_screen_get_display (GdkScreen *screen)
 {
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), NULL);
-
   return GDK_BROADWAY_SCREEN (screen)->display;
 }
 
 static gint
 gdk_broadway_screen_get_width (GdkScreen *screen)
 {
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), 0);
-
   return GDK_BROADWAY_SCREEN (screen)->width;
 }
 
 static gint
 gdk_broadway_screen_get_height (GdkScreen *screen)
 {
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), 0);
-
   return GDK_BROADWAY_SCREEN (screen)->height;
 }
 
 static gint
 gdk_broadway_screen_get_width_mm (GdkScreen *screen)
 {
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), 0);
-
   return gdk_screen_get_width (screen) * 25.4 / 96;
 }
 
 static gint
 gdk_broadway_screen_get_height_mm (GdkScreen *screen)
 {
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), 0);
-
   return gdk_screen_get_height (screen) * 25.4 / 96;
 }
 
 static gint
 gdk_broadway_screen_get_number (GdkScreen *screen)
 {
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), 0);
-
   return 0;
 }
 
 static GdkWindow *
 gdk_broadway_screen_get_root_window (GdkScreen *screen)
 {
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), NULL);
-
   return GDK_BROADWAY_SCREEN (screen)->root_window;
 }
 
 void
-_gdk_broadway_screen_size_changed (GdkScreen *screen, BroadwayInputScreenResizeNotify *msg)
+_gdk_broadway_screen_size_changed (GdkScreen                       *screen,
+                                   BroadwayInputScreenResizeNotify *msg)
 {
   GdkBroadwayScreen *broadway_screen = GDK_BROADWAY_SCREEN (screen);
   gint width, height;
@@ -150,16 +137,12 @@ gdk_broadway_screen_finalize (GObject *object)
 static gint
 gdk_broadway_screen_get_n_monitors (GdkScreen *screen)
 {
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), 0);
-
   return 1;
 }
 
 static gint
 gdk_broadway_screen_get_primary_monitor (GdkScreen *screen)
 {
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), 0);
-
   return 0;
 }
 
@@ -167,7 +150,6 @@ static gint
 gdk_broadway_screen_get_monitor_width_mm (GdkScreen *screen,
 					  gint       monitor_num)
 {
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), -1);
   g_return_val_if_fail (monitor_num == 0, -1);
 
   return gdk_screen_get_width_mm (screen);
@@ -177,7 +159,6 @@ static gint
 gdk_broadway_screen_get_monitor_height_mm (GdkScreen *screen,
 					   gint       monitor_num)
 {
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), -1);
   g_return_val_if_fail (monitor_num == 0, -1);
 
   return gdk_screen_get_height_mm (screen);
@@ -187,7 +168,6 @@ static gchar *
 gdk_broadway_screen_get_monitor_plug_name (GdkScreen *screen,
 					   gint       monitor_num)
 {
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), NULL);
   g_return_val_if_fail (monitor_num == 0, NULL);
 
   return g_strdup ("browser");
@@ -200,7 +180,6 @@ gdk_broadway_screen_get_monitor_geometry (GdkScreen    *screen,
 {
   GdkBroadwayScreen *broadway_screen = GDK_BROADWAY_SCREEN (screen);
 
-  g_return_if_fail (GDK_IS_SCREEN (screen));
   g_return_if_fail (monitor_num == 0);
 
   if (dest)
@@ -215,11 +194,7 @@ gdk_broadway_screen_get_monitor_geometry (GdkScreen    *screen,
 static GdkVisual *
 gdk_broadway_screen_get_rgba_visual (GdkScreen *screen)
 {
-  GdkBroadwayScreen *broadway_screen;
-
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), NULL);
-
-  broadway_screen = GDK_BROADWAY_SCREEN (screen);
+  GdkBroadwayScreen *broadway_screen = GDK_BROADWAY_SCREEN (screen);
 
   return broadway_screen->rgba_visual;
 }
@@ -254,8 +229,6 @@ _gdk_broadway_screen_setup (GdkScreen *screen)
 static gboolean
 gdk_broadway_screen_is_composited (GdkScreen *screen)
 {
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), FALSE);
-
   return FALSE;
 }
 
@@ -263,8 +236,6 @@ gdk_broadway_screen_is_composited (GdkScreen *screen)
 static gchar *
 gdk_broadway_screen_make_display_name (GdkScreen *screen)
 {
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), NULL);
-
   return g_strdup ("browser");
 }
 
diff --git a/gdk/gdkscreen.c b/gdk/gdkscreen.c
index 9493e168ff..0ed04b14c1 100644
--- a/gdk/gdkscreen.c
+++ b/gdk/gdkscreen.c
@@ -548,7 +548,9 @@ gdk_screen_set_property (GObject      *object,
 GdkDisplay *
 gdk_screen_get_display (GdkScreen *screen)
 {
-  return GDK_SCREEN_GET_CLASS(screen)->get_display (screen);
+  g_return_val_if_fail (GDK_IS_SCREEN (screen), NULL);
+
+  return GDK_SCREEN_GET_CLASS (screen)->get_display (screen);
 }
 
 
@@ -565,7 +567,9 @@ gdk_screen_get_display (GdkScreen *screen)
 gint
 gdk_screen_get_width (GdkScreen *screen)
 {
-  return GDK_SCREEN_GET_CLASS(screen)->get_width (screen);
+  g_return_val_if_fail (GDK_IS_SCREEN (screen), 0);
+
+  return GDK_SCREEN_GET_CLASS (screen)->get_width (screen);
 }
 
 /**
@@ -581,7 +585,9 @@ gdk_screen_get_width (GdkScreen *screen)
 gint
 gdk_screen_get_height (GdkScreen *screen)
 {
-  return GDK_SCREEN_GET_CLASS(screen)->get_height (screen);
+  g_return_val_if_fail (GDK_IS_SCREEN (screen), 0);
+
+  return GDK_SCREEN_GET_CLASS (screen)->get_height (screen);
 }
 
 /**
@@ -598,7 +604,9 @@ gdk_screen_get_height (GdkScreen *screen)
 gint
 gdk_screen_get_width_mm (GdkScreen *screen)
 {
-  return GDK_SCREEN_GET_CLASS(screen)->get_width_mm (screen);
+  g_return_val_if_fail (GDK_IS_SCREEN (screen), 0);
+
+  return GDK_SCREEN_GET_CLASS (screen)->get_width_mm (screen);
 }
 
 /**
@@ -615,7 +623,9 @@ gdk_screen_get_width_mm (GdkScreen *screen)
 gint
 gdk_screen_get_height_mm (GdkScreen *screen)
 {
-  return GDK_SCREEN_GET_CLASS(screen)->get_height_mm (screen);
+  g_return_val_if_fail (GDK_IS_SCREEN (screen), 0);
+
+  return GDK_SCREEN_GET_CLASS (screen)->get_height_mm (screen);
 }
 
 /**
@@ -632,7 +642,9 @@ gdk_screen_get_height_mm (GdkScreen *screen)
 gint
 gdk_screen_get_number (GdkScreen *screen)
 {
-  return GDK_SCREEN_GET_CLASS(screen)->get_number (screen);
+  g_return_val_if_fail (GDK_IS_SCREEN (screen), 0);
+
+  return GDK_SCREEN_GET_CLASS (screen)->get_number (screen);
 }
 
 /**
@@ -648,7 +660,9 @@ gdk_screen_get_number (GdkScreen *screen)
 GdkWindow *
 gdk_screen_get_root_window (GdkScreen *screen)
 {
-  return GDK_SCREEN_GET_CLASS(screen)->get_root_window (screen);
+  g_return_val_if_fail (GDK_IS_SCREEN (screen), NULL);
+
+  return GDK_SCREEN_GET_CLASS (screen)->get_root_window (screen);
 }
 
 /**
@@ -664,7 +678,9 @@ gdk_screen_get_root_window (GdkScreen *screen)
 gint
 gdk_screen_get_n_monitors (GdkScreen *screen)
 {
-  return GDK_SCREEN_GET_CLASS(screen)->get_n_monitors (screen);
+  g_return_val_if_fail (GDK_IS_SCREEN (screen), 0);
+
+  return GDK_SCREEN_GET_CLASS (screen)->get_n_monitors (screen);
 }
 
 /**
@@ -687,7 +703,9 @@ gdk_screen_get_n_monitors (GdkScreen *screen)
 gint
 gdk_screen_get_primary_monitor (GdkScreen *screen)
 {
-  return GDK_SCREEN_GET_CLASS(screen)->get_primary_monitor (screen);
+  g_return_val_if_fail (GDK_IS_SCREEN (screen), 0);
+
+  return GDK_SCREEN_GET_CLASS (screen)->get_primary_monitor (screen);
 }
 
 /**
@@ -705,7 +723,10 @@ gint
 gdk_screen_get_monitor_width_mm	(GdkScreen *screen,
 				 gint       monitor_num)
 {
-  return GDK_SCREEN_GET_CLASS(screen)->get_monitor_width_mm (screen, monitor_num);
+  g_return_val_if_fail (GDK_IS_SCREEN (screen), -1);
+  g_return_val_if_fail (monitor_num >= 0, -1);
+
+  return GDK_SCREEN_GET_CLASS (screen)->get_monitor_width_mm (screen, monitor_num);
 }
 
 /**
@@ -723,7 +744,10 @@ gint
 gdk_screen_get_monitor_height_mm (GdkScreen *screen,
                                   gint       monitor_num)
 {
-  return GDK_SCREEN_GET_CLASS(screen)->get_monitor_height_mm (screen, monitor_num);
+  g_return_val_if_fail (GDK_IS_SCREEN (screen), -1);
+  g_return_val_if_fail (monitor_num >= 0, -1);
+
+  return GDK_SCREEN_GET_CLASS (screen)->get_monitor_height_mm (screen, monitor_num);
 }
 
 /**
@@ -744,7 +768,10 @@ gchar *
 gdk_screen_get_monitor_plug_name (GdkScreen *screen,
 				  gint       monitor_num)
 {
-  return GDK_SCREEN_GET_CLASS(screen)->get_monitor_plug_name (screen, monitor_num);
+  g_return_val_if_fail (GDK_IS_SCREEN (screen), NULL);
+  g_return_val_if_fail (monitor_num >= 0, NULL);
+
+  return GDK_SCREEN_GET_CLASS (screen)->get_monitor_plug_name (screen, monitor_num);
 }
 
 /**
@@ -770,6 +797,9 @@ gdk_screen_get_monitor_geometry (GdkScreen    *screen,
 				 gint          monitor_num,
 				 GdkRectangle *dest)
 {
+  g_return_if_fail (GDK_IS_SCREEN (screen));
+  g_return_if_fail (monitor_num >= 0);
+
   GDK_SCREEN_GET_CLASS(screen)->get_monitor_geometry (screen, monitor_num, dest);
 }
 
@@ -797,7 +827,10 @@ gdk_screen_get_monitor_workarea (GdkScreen    *screen,
                                  gint          monitor_num,
                                  GdkRectangle *dest)
 {
-  GDK_SCREEN_GET_CLASS(screen)->get_monitor_workarea (screen, monitor_num, dest);
+  g_return_if_fail (GDK_IS_SCREEN (screen));
+  g_return_if_fail (monitor_num >= 0);
+
+  GDK_SCREEN_GET_CLASS (screen)->get_monitor_workarea (screen, monitor_num, dest);
 }
 
 /**
@@ -819,7 +852,9 @@ gdk_screen_get_monitor_workarea (GdkScreen    *screen,
 GList *
 gdk_screen_list_visuals (GdkScreen *screen)
 {
-  return GDK_SCREEN_GET_CLASS(screen)->list_visuals (screen);
+  g_return_val_if_fail (GDK_IS_SCREEN (screen), NULL);
+
+  return GDK_SCREEN_GET_CLASS (screen)->list_visuals (screen);
 }
 
 /**
@@ -837,7 +872,9 @@ gdk_screen_list_visuals (GdkScreen *screen)
 GdkVisual *
 gdk_screen_get_system_visual (GdkScreen * screen)
 {
-  return GDK_SCREEN_GET_CLASS(screen)->get_system_visual (screen);
+  g_return_val_if_fail (GDK_IS_SCREEN (screen), NULL);
+
+  return GDK_SCREEN_GET_CLASS (screen)->get_system_visual (screen);
 }
 
 /**
@@ -866,7 +903,9 @@ gdk_screen_get_system_visual (GdkScreen * screen)
 GdkVisual *
 gdk_screen_get_rgba_visual (GdkScreen *screen)
 {
-  return GDK_SCREEN_GET_CLASS(screen)->get_rgba_visual (screen);
+  g_return_val_if_fail (GDK_IS_SCREEN (screen), NULL);
+
+  return GDK_SCREEN_GET_CLASS (screen)->get_rgba_visual (screen);
 }
 
 /**
@@ -888,7 +927,9 @@ gdk_screen_get_rgba_visual (GdkScreen *screen)
 gboolean
 gdk_screen_is_composited (GdkScreen *screen)
 {
-  return GDK_SCREEN_GET_CLASS(screen)->is_composited (screen);
+  g_return_val_if_fail (GDK_IS_SCREEN (screen), FALSE);
+
+  return GDK_SCREEN_GET_CLASS (screen)->is_composited (screen);
 }
 
 /**
@@ -905,7 +946,9 @@ gdk_screen_is_composited (GdkScreen *screen)
 gchar *
 gdk_screen_make_display_name (GdkScreen *screen)
 {
-  return GDK_SCREEN_GET_CLASS(screen)->make_display_name (screen);
+  g_return_val_if_fail (GDK_IS_SCREEN (screen), NULL);
+
+  return GDK_SCREEN_GET_CLASS (screen)->make_display_name (screen);
 }
 
 /**
@@ -934,7 +977,9 @@ gdk_screen_make_display_name (GdkScreen *screen)
 GdkWindow *
 gdk_screen_get_active_window (GdkScreen *screen)
 {
-  return GDK_SCREEN_GET_CLASS(screen)->get_active_window (screen);
+  g_return_val_if_fail (GDK_IS_SCREEN (screen), NULL);
+
+  return GDK_SCREEN_GET_CLASS (screen)->get_active_window (screen);
 }
 
 /**
@@ -966,7 +1011,9 @@ gdk_screen_get_active_window (GdkScreen *screen)
 GList *
 gdk_screen_get_window_stack (GdkScreen *screen)
 {
-  return GDK_SCREEN_GET_CLASS(screen)->get_window_stack (screen);
+  g_return_val_if_fail (GDK_IS_SCREEN (screen), NULL);
+
+  return GDK_SCREEN_GET_CLASS (screen)->get_window_stack (screen);
 }
 
 /**
@@ -991,5 +1038,9 @@ gdk_screen_get_setting (GdkScreen   *screen,
 			const gchar *name,
 			GValue      *value)
 {
-  return GDK_SCREEN_GET_CLASS(screen)->get_setting (screen, name, value);
+  g_return_val_if_fail (GDK_IS_SCREEN (screen), FALSE);
+  g_return_val_if_fail (name != NULL, FALSE);
+  g_return_val_if_fail (value != NULL, FALSE);
+
+  return GDK_SCREEN_GET_CLASS (screen)->get_setting (screen, name, value);
 }
diff --git a/gdk/quartz/gdkscreen-quartz.c b/gdk/quartz/gdkscreen-quartz.c
index d104571ce6..55f4ca08a1 100644
--- a/gdk/quartz/gdkscreen-quartz.c
+++ b/gdk/quartz/gdkscreen-quartz.c
@@ -291,7 +291,6 @@ gdk_quartz_screen_get_display (GdkScreen *screen)
   return _gdk_display;
 }
 
-
 static GdkWindow *
 gdk_quartz_screen_get_root_window (GdkScreen *screen)
 {
@@ -304,7 +303,7 @@ gdk_quartz_screen_get_number (GdkScreen *screen)
   return 0;
 }
 
-gchar * 
+gchar *
 _gdk_windowing_substitute_screen_number (const gchar *display_name,
 					 int          screen_number)
 {
diff --git a/gdk/wayland/gdkscreen-wayland.c b/gdk/wayland/gdkscreen-wayland.c
index 310fc15a72..47f70ef41e 100644
--- a/gdk/wayland/gdkscreen-wayland.c
+++ b/gdk/wayland/gdkscreen-wayland.c
@@ -163,72 +163,54 @@ gdk_wayland_screen_finalize (GObject *object)
 static GdkDisplay *
 gdk_wayland_screen_get_display (GdkScreen *screen)
 {
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), NULL);
-
   return GDK_SCREEN_WAYLAND (screen)->display;
 }
 
 static gint
 gdk_wayland_screen_get_width (GdkScreen *screen)
 {
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), 0);
-
   return GDK_SCREEN_WAYLAND (screen)->width;
 }
 
 static gint
 gdk_wayland_screen_get_height (GdkScreen *screen)
 {
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), 0);
-
   return GDK_SCREEN_WAYLAND (screen)->height;
 }
 
 static gint
 gdk_wayland_screen_get_width_mm (GdkScreen *screen)
 {
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), 0);
-
   return GDK_SCREEN_WAYLAND (screen)->width_mm;
 }
 
 static gint
 gdk_wayland_screen_get_height_mm (GdkScreen *screen)
 {
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), 0);
-
   return GDK_SCREEN_WAYLAND (screen)->height_mm;
 }
 
 static gint
 gdk_wayland_screen_get_number (GdkScreen *screen)
 {
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), 0);
-
   return 0;
 }
 
 static GdkWindow *
 gdk_wayland_screen_get_root_window (GdkScreen *screen)
 {
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), NULL);
-
   return GDK_SCREEN_WAYLAND (screen)->root_window;
 }
 
 static gint
 gdk_wayland_screen_get_n_monitors (GdkScreen *screen)
 {
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), 0);
-
   return GDK_SCREEN_WAYLAND (screen)->n_monitors;
 }
 
 static gint
 gdk_wayland_screen_get_primary_monitor (GdkScreen *screen)
 {
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), 0);
-
   return GDK_SCREEN_WAYLAND (screen)->primary_monitor;
 }
 
@@ -238,8 +220,6 @@ gdk_wayland_screen_get_monitor_width_mm	(GdkScreen *screen,
 {
   GdkScreenWayland *screen_wayland = GDK_SCREEN_WAYLAND (screen);
 
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), -1);
-  g_return_val_if_fail (monitor_num >= 0, -1);
   g_return_val_if_fail (monitor_num < screen_wayland->n_monitors, -1);
 
   return screen_wayland->monitors[monitor_num].width_mm;
@@ -251,8 +231,6 @@ gdk_wayland_screen_get_monitor_height_mm (GdkScreen *screen,
 {
   GdkScreenWayland *screen_wayland = GDK_SCREEN_WAYLAND (screen);
 
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), -1);
-  g_return_val_if_fail (monitor_num >= 0, -1);
   g_return_val_if_fail (monitor_num < screen_wayland->n_monitors, -1);
 
   return screen_wayland->monitors[monitor_num].height_mm;
@@ -264,8 +242,6 @@ gdk_wayland_screen_get_monitor_plug_name (GdkScreen *screen,
 {
   GdkScreenWayland *screen_wayland = GDK_SCREEN_WAYLAND (screen);
 
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), NULL);
-  g_return_val_if_fail (monitor_num >= 0, NULL);
   g_return_val_if_fail (monitor_num < screen_wayland->n_monitors, NULL);
 
   return g_strdup (screen_wayland->monitors[monitor_num].output_name);
@@ -278,8 +254,6 @@ gdk_wayland_screen_get_monitor_geometry (GdkScreen    *screen,
 {
   GdkScreenWayland *screen_wayland = GDK_SCREEN_WAYLAND (screen);
 
-  g_return_if_fail (GDK_IS_SCREEN (screen));
-  g_return_if_fail (monitor_num >= 0);
   g_return_if_fail (monitor_num < screen_wayland->n_monitors);
 
   if (dest)
@@ -313,8 +287,6 @@ gdk_wayland_screen_make_display_name (GdkScreen *screen)
 static GdkWindow *
 gdk_wayland_screen_get_active_window (GdkScreen *screen)
 {
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), NULL);
-
   return NULL;
 }
 
diff --git a/gdk/win32/gdkscreen-win32.c b/gdk/win32/gdkscreen-win32.c
index 457858a2e7..6ee2242a22 100644
--- a/gdk/win32/gdkscreen-win32.c
+++ b/gdk/win32/gdkscreen-win32.c
@@ -27,13 +27,16 @@ struct _GdkWin32Screen
 {
   GdkScreen parent_instance;
 };
+
 struct _GdkWin32ScreenClass
 {
   GdkScreenClass parent_class;
 };
+
 G_DEFINE_TYPE (GdkWin32Screen, gdk_win32_screen, GDK_TYPE_SCREEN)
+
 static void
-gdk_win32_screen_init(GdkWin32Screen *display)
+gdk_win32_screen_init (GdkWin32Screen *display)
 {
 }
 
@@ -91,45 +94,41 @@ gdk_win32_screen_get_primary_monitor (GdkScreen *screen)
 
 static gint
 gdk_win32_screen_get_monitor_width_mm (GdkScreen *screen,
-                                 gint       num_monitor)
+                                       gint       num_monitor)
 {
   g_return_val_if_fail (screen == _gdk_screen, 0);
   g_return_val_if_fail (num_monitor < _gdk_num_monitors, 0);
-  g_return_val_if_fail (num_monitor >= 0, 0);
 
   return _gdk_monitors[num_monitor].width_mm;
 }
 
 static gint
 gdk_win32_screen_get_monitor_height_mm (GdkScreen *screen,
-                                  gint       num_monitor)
+                                        gint       num_monitor)
 {
   g_return_val_if_fail (screen == _gdk_screen, 0);
   g_return_val_if_fail (num_monitor < _gdk_num_monitors, 0);
-  g_return_val_if_fail (num_monitor >= 0, 0);
 
   return _gdk_monitors[num_monitor].height_mm;
 }
 
 static gchar *
 gdk_win32_screen_get_monitor_plug_name (GdkScreen *screen,
-                                  gint       num_monitor)
+                                        gint       num_monitor)
 {
   g_return_val_if_fail (screen == _gdk_screen, 0);
   g_return_val_if_fail (num_monitor < _gdk_num_monitors, 0);
-  g_return_val_if_fail (num_monitor >= 0, 0);
 
   return g_strdup (_gdk_monitors[num_monitor].name);
 }
 
 static void
-gdk_win32_screen_get_monitor_geometry (GdkScreen    *screen, 
-				 gint          num_monitor,
-				 GdkRectangle *dest)
+gdk_win32_screen_get_monitor_geometry (GdkScreen    *screen,
+                                       gint          num_monitor,
+                                       GdkRectangle *dest)
 {
   g_return_if_fail (screen == _gdk_screen);
   g_return_if_fail (num_monitor < _gdk_num_monitors);
-  g_return_if_fail (num_monitor >= 0);
 
   *dest = _gdk_monitors[num_monitor].rect;
 }
@@ -141,16 +140,16 @@ gdk_win32_screen_get_rgba_visual (GdkScreen *screen)
 
   return NULL;
 }
-  
+
 static gint
 gdk_win32_screen_get_number (GdkScreen *screen)
 {
-  g_return_val_if_fail (screen == _gdk_screen, 0);  
-  
+  g_return_val_if_fail (screen == _gdk_screen, 0);
+
   return 0;
 }
 
-gchar * 
+gchar *
 _gdk_windowing_substitute_screen_number (const gchar *display_name,
 					 int          screen_number)
 {
diff --git a/gdk/x11/gdkscreen-x11.c b/gdk/x11/gdkscreen-x11.c
index 58bcd92ad0..a1986d7c0a 100644
--- a/gdk/x11/gdkscreen-x11.c
+++ b/gdk/x11/gdkscreen-x11.c
@@ -93,56 +93,42 @@ gdk_x11_screen_init (GdkX11Screen *screen)
 static GdkDisplay *
 gdk_x11_screen_get_display (GdkScreen *screen)
 {
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), NULL);
-
   return GDK_X11_SCREEN (screen)->display;
 }
 
 static gint
 gdk_x11_screen_get_width (GdkScreen *screen)
 {
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), 0);
-
   return WidthOfScreen (GDK_X11_SCREEN (screen)->xscreen);
 }
 
 static gint
 gdk_x11_screen_get_height (GdkScreen *screen)
 {
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), 0);
-
   return HeightOfScreen (GDK_X11_SCREEN (screen)->xscreen);
 }
 
 static gint
 gdk_x11_screen_get_width_mm (GdkScreen *screen)
 {
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), 0);  
-
   return WidthMMOfScreen (GDK_X11_SCREEN (screen)->xscreen);
 }
 
 static gint
 gdk_x11_screen_get_height_mm (GdkScreen *screen)
 {
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), 0);
-
   return HeightMMOfScreen (GDK_X11_SCREEN (screen)->xscreen);
 }
 
 static gint
 gdk_x11_screen_get_number (GdkScreen *screen)
 {
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), 0);
-  
   return GDK_X11_SCREEN (screen)->screen_num;
 }
 
 static GdkWindow *
 gdk_x11_screen_get_root_window (GdkScreen *screen)
 {
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), NULL);
-
   return GDK_X11_SCREEN (screen)->root_window;
 }
 
@@ -212,27 +198,21 @@ gdk_x11_screen_finalize (GObject *object)
 static gint
 gdk_x11_screen_get_n_monitors (GdkScreen *screen)
 {
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), 0);
-
   return GDK_X11_SCREEN (screen)->n_monitors;
 }
 
 static gint
 gdk_x11_screen_get_primary_monitor (GdkScreen *screen)
 {
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), 0);
-
   return GDK_X11_SCREEN (screen)->primary_monitor;
 }
 
 static gint
-gdk_x11_screen_get_monitor_width_mm	(GdkScreen *screen,
-					 gint       monitor_num)
+gdk_x11_screen_get_monitor_width_mm (GdkScreen *screen,
+                                     gint       monitor_num)
 {
   GdkX11Screen *x11_screen = GDK_X11_SCREEN (screen);
 
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), -1);
-  g_return_val_if_fail (monitor_num >= 0, -1);
   g_return_val_if_fail (monitor_num < x11_screen->n_monitors, -1);
 
   return x11_screen->monitors[monitor_num].width_mm;
@@ -244,8 +224,6 @@ gdk_x11_screen_get_monitor_height_mm (GdkScreen *screen,
 {
   GdkX11Screen *x11_screen = GDK_X11_SCREEN (screen);
 
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), -1);
-  g_return_val_if_fail (monitor_num >= 0, -1);
   g_return_val_if_fail (monitor_num < x11_screen->n_monitors, -1);
 
   return x11_screen->monitors[monitor_num].height_mm;
@@ -257,8 +235,6 @@ gdk_x11_screen_get_monitor_plug_name (GdkScreen *screen,
 {
   GdkX11Screen *x11_screen = GDK_X11_SCREEN (screen);
 
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), NULL);
-  g_return_val_if_fail (monitor_num >= 0, NULL);
   g_return_val_if_fail (monitor_num < x11_screen->n_monitors, NULL);
 
   return g_strdup (x11_screen->monitors[monitor_num].output_name);
@@ -297,8 +273,6 @@ gdk_x11_screen_get_monitor_geometry (GdkScreen    *screen,
 {
   GdkX11Screen *x11_screen = GDK_X11_SCREEN (screen);
 
-  g_return_if_fail (GDK_IS_SCREEN (screen));
-  g_return_if_fail (monitor_num >= 0);
   g_return_if_fail (monitor_num < x11_screen->n_monitors);
 
   if (dest)
@@ -415,11 +389,7 @@ gdk_x11_screen_get_monitor_workarea (GdkScreen    *screen,
 static GdkVisual *
 gdk_x11_screen_get_rgba_visual (GdkScreen *screen)
 {
-  GdkX11Screen *x11_screen;
-
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), NULL);
-
-  x11_screen = GDK_X11_SCREEN (screen);
+  GdkX11Screen *x11_screen = GDK_X11_SCREEN (screen);
 
   return x11_screen->rgba_visual;
 }
@@ -941,11 +911,7 @@ _gdk_x11_screen_setup (GdkScreen *screen)
 static gboolean
 gdk_x11_screen_is_composited (GdkScreen *screen)
 {
-  GdkX11Screen *x11_screen;
-
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), FALSE);
-
-  x11_screen = GDK_X11_SCREEN (screen);
+  GdkX11Screen *x11_screen = GDK_X11_SCREEN (screen);
 
   return x11_screen->is_composited;
 }
@@ -1093,8 +1059,6 @@ gdk_x11_screen_make_display_name (GdkScreen *screen)
 {
   const gchar *old_display;
 
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), NULL);
-
   old_display = gdk_display_get_name (gdk_screen_get_display (screen));
 
   return substitute_screen_number (old_display,
@@ -1104,7 +1068,7 @@ gdk_x11_screen_make_display_name (GdkScreen *screen)
 static GdkWindow *
 gdk_x11_screen_get_active_window (GdkScreen *screen)
 {
-  GdkX11Screen *x11_screen;
+  GdkX11Screen *x11_screen = GDK_X11_SCREEN (screen);
   GdkWindow *ret = NULL;
   Atom type_return;
   gint format_return;
@@ -1112,14 +1076,10 @@ gdk_x11_screen_get_active_window (GdkScreen *screen)
   gulong bytes_after_return;
   guchar *data = NULL;
 
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), NULL);
-
   if (!gdk_x11_screen_supports_net_wm_hint (screen,
                                             gdk_atom_intern_static_string ("_NET_ACTIVE_WINDOW")))
     return NULL;
 
-  x11_screen = GDK_X11_SCREEN (screen);
-
   if (XGetWindowProperty (x11_screen->xdisplay, x11_screen->xroot_window,
 	                  gdk_x11_get_xatom_by_name_for_display (x11_screen->display,
 			                                         "_NET_ACTIVE_WINDOW"),
@@ -1149,7 +1109,7 @@ gdk_x11_screen_get_active_window (GdkScreen *screen)
 static GList *
 gdk_x11_screen_get_window_stack (GdkScreen *screen)
 {
-  GdkX11Screen *x11_screen;
+  GdkX11Screen *x11_screen = GDK_X11_SCREEN (screen);
   GList *ret = NULL;
   Atom type_return;
   gint format_return;
@@ -1157,14 +1117,10 @@ gdk_x11_screen_get_window_stack (GdkScreen *screen)
   gulong bytes_after_return;
   guchar *data = NULL;
 
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), NULL);
-
   if (!gdk_x11_screen_supports_net_wm_hint (screen,
                                             gdk_atom_intern_static_string ("_NET_CLIENT_LIST_STACKING")))
     return NULL;
 
-  x11_screen = GDK_X11_SCREEN (screen);
-
   if (XGetWindowProperty (x11_screen->xdisplay, x11_screen->xroot_window,
 	                  gdk_x11_get_xatom_by_name_for_display (x11_screen->display,
 			                                         "_NET_CLIENT_LIST_STACKING"),
@@ -1219,19 +1175,14 @@ gdk_x11_screen_get_setting (GdkScreen   *screen,
 			    const gchar *name,
 			    GValue      *value)
 {
-
+  GdkX11Screen *x11_screen = GDK_X11_SCREEN (screen);
   const char *xsettings_name = NULL;
   XSettingsResult result;
   XSettingsSetting *setting = NULL;
-  GdkX11Screen *x11_screen;
   gboolean success = FALSE;
   gint i;
   GValue tmp_val = G_VALUE_INIT;
 
-  g_return_val_if_fail (GDK_IS_SCREEN (screen), FALSE);
-
-  x11_screen = GDK_X11_SCREEN (screen);
-
   for (i = 0; i < GDK_SETTINGS_N_ELEMENTS(); i++)
     if (strcmp (GDK_SETTINGS_GDK_NAME (i), name) == 0)
       {