discontinue use of some deprecated methods if built with gtk 3.22+

meson.build

@@ -30,7 +30,7 @@ webext_deps = [webkit2_webext, lightdm_gobject]
 
 has_webkitgtk_2_14 = webkit2.version().version_compare('>=2.14.0')
 has_lightdm_1_19_2 = lightdm_gobject.version().version_compare('>=1.19.2')
-
+has_gtk_3_22 = gtk3.version().version_compare('>=3.22')
 
 # =================================== #
 # ------->>> Configuration <<<------- #
@@ -56,12 +56,18 @@ conf.set('DESKTOP_DIR', '"@0@"'.format(get_option('with-desktop-dir')))
 
 conf.set('WEBEXT_DIR', '"@0@"'.format(get_option('with-webext-dir')))
 
-conf.set('HAS_WEBKITGTK_2_14', has_webkitgtk_2_14)
+if has_webkitgtk_2_14
+  conf.set('HAS_WEBKITGTK_2_14', has_webkitgtk_2_14)
+endif
 
 if has_lightdm_1_19_2
   conf.set('HAS_LIGHTDM_1_19_2', has_lightdm_1_19_2)
 endif
 
+if has_gtk_3_22
+  conf.set('HAS_GTK_3_22', has_gtk_3_22)
+endif
+
 
 # ===================================== #
 # ------->>> Sub Directories <<<------- #

src/greeter.c

@@ -373,7 +373,14 @@ main(int argc, char **argv) {
 	screen = gtk_window_get_screen(GTK_WINDOW(window));
 
 	gtk_window_set_decorated(GTK_WINDOW(window), FALSE);
-	gdk_screen_get_monitor_geometry(screen, gdk_screen_get_primary_monitor(screen), &geometry);
+
+	#ifdef HAS_GTK_3_22
+		GdkMonitor *monitor = gdk_display_get_primary_monitor(default_display);
+		gdk_monitor_get_geometry(monitor, &geometry);
+	#else
+		gdk_screen_get_monitor_geometry(screen, gdk_screen_get_primary_monitor(screen), &geometry);
+	#endif
+
 	gtk_window_set_default_size(GTK_WINDOW(window), geometry.width, geometry.height);
 	gtk_window_move(GTK_WINDOW(window), geometry.x, geometry.y);