Minor alteration to this patch to get it to cleanly apply at 1.26.0,
changed "int pkexec_uid;" to "unsigned int pkexec_uid;" in chunk #2.

--- mate-control-center-1.18.1/capplets/display/xrandr-capplet.c.~1~	2017-04-05 23:22:53.000000000 +0300
+++ mate-control-center-1.18.1/capplets/display/xrandr-capplet.c	2017-05-24 09:08:24.255471398 +0300
@@ -2349,7 +2349,11 @@
 
     source_filename = mate_rr_config_get_intended_filename ();
 
+#ifdef __sun__
+    command_line = g_strdup_printf ("/usr/bin/gksu -u root %s/mate-display-properties-install-systemwide %s %s",
+#else
     command_line = g_strdup_printf ("pkexec %s/mate-display-properties-install-systemwide %s %s",
+#endif
 				    SBINDIR,
 				    source_filename,
 				    dest_basename);
--- mate-control-center-1.14.0/capplets/display/mate-display-properties-install-systemwide.c.~1~	2016-01-30 21:03:48.000000000 +0300
+++ mate-control-center-1.14.0/capplets/display/mate-display-properties-install-systemwide.c	2016-07-28 13:37:44.255108119 +0300
@@ -130,8 +130,10 @@
 	uid_t uid, euid;
 	const char *source_filename;
 	const char *dest_name;
+#ifndef __sun__
 	const char *pkexec_uid_str;
 	unsigned int pkexec_uid;
+#endif
 	struct stat statbuf;
 	int err;
 	int source_fd;
@@ -197,6 +199,7 @@
 		return EXIT_FAILURE;
 	}
 
+#ifndef __sun__
 	/* We only copy files that are really owned by the calling user */
 
 	pkexec_uid_str = g_getenv ("PKEXEC_UID");
@@ -215,6 +218,7 @@
 		g_print (_("%s must be owned by you\n"), source_filename);
 		return EXIT_FAILURE;
 	}
+#endif
 
 	/* We only accept basenames for the destination */