diff -Naur rdesktop/doc/rdesktop.1 rdesktop-modified/doc/rdesktop.1
--- rdesktop/doc/rdesktop.1	2006-11-02 07:52:01.000000000 +1100
+++ rdesktop-modified/doc/rdesktop.1	2006-12-18 00:46:09.000000000 +1100
@@ -86,6 +86,22 @@
 
 Example: rdesktop -A -s 'seamlessrdpshell notepad'.
 .TP
+.BR "-M <control socket path>"
+Enable SeamlessRDP master mode. This mode allows additional applications to be
+launched from a single SeamlessRDP session as opposed to requiring one session
+per application. A control socket path must be specified for use by slave mode
+invocations.
+
+Example: rdesktop -A -s 'seamlessrdpshell notepad' -M /tmp/rdesktop-socket
+.TP
+.BR "-l <command>"
+Use SeamlessRDP slave mode to execute an additional command within the master
+SeamlessRDP session. When using this option, a control socket path must be
+specified instead of a server, and all other options will be ignored. Note
+that a shell does not have to be specified, only the command to be executed.
+
+Example: rdesktop -l 'notepad' /tmp/rdesktop-socket
+.TP
 .BR "-B"
 Use the BackingStore of the Xserver instead of the integrated one in
 rdesktop.
diff -Naur rdesktop/proto.h rdesktop-modified/proto.h
--- rdesktop/proto.h	2006-12-08 02:23:45.000000000 +1100
+++ rdesktop-modified/proto.h	2006-12-18 01:16:44.000000000 +1100
@@ -303,6 +303,7 @@
 void seamless_select_timeout(struct timeval *tv);
 unsigned int seamless_send_zchange(unsigned long id, unsigned long below, unsigned long flags);
 unsigned int seamless_send_focus(unsigned long id, unsigned long flags);
+unsigned int seamless_send_spawn(char *cmdline);
 /* scard.c */
 void scardSetInfo(uint32 device, uint32 id, uint32 bytes_out);
 int scard_enum_devices(uint32 * id, char *optarg);
diff -Naur rdesktop/rdesktop.c rdesktop-modified/rdesktop.c
--- rdesktop/rdesktop.c	2006-11-07 10:05:39.000000000 +1100
+++ rdesktop-modified/rdesktop.c	2006-12-18 01:16:45.000000000 +1100
@@ -29,6 +29,7 @@
 #include <ctype.h>		/* toupper */
 #include <errno.h>
 #include "rdesktop.h"
+#include "seamless.h"
 
 #ifdef HAVE_LOCALE_H
 #include <locale.h>
@@ -91,6 +92,12 @@
 BOOL g_owncolmap = False;
 BOOL g_ownbackstore = True;	/* We can't rely on external BackingStore */
 BOOL g_seamless_rdp = False;
+
+/* Master socket identifier */
+char *master_socket = NULL;
+/* Command line to execute in slave mode */
+char *slave_cmdline = NULL;
+
 uint32 g_embed_wnd;
 uint32 g_rdp5_performanceflags =
 	RDP5_NO_WALLPAPER | RDP5_NO_FULLWINDOWDRAG | RDP5_NO_MENUANIMATIONS;
@@ -122,6 +129,10 @@
 rdp2vnc_connect(char *server, uint32 flags, char *domain, char *password,
 		char *shell, char *directory);
 #endif
+
+// Send message to rdesktop running in SeamlessrRDP master mode
+void send_seamless_slave_message(char *cmdline);
+
 /* Display usage information */
 static void
 usage(char *program)
@@ -131,6 +142,7 @@
 	fprintf(stderr, "See http://www.rdesktop.org/ for more information.\n\n");
 
 	fprintf(stderr, "Usage: %s [options] server[:port]\n", program);
+	fprintf(stderr, "       %s -l <command> <control socket path>\n", program);
 #ifdef RDP2VNC
 	fprintf(stderr, "   -V: vnc port\n");
 	fprintf(stderr, "   -Q: defer time (ms)\n");
@@ -149,6 +161,8 @@
 	fprintf(stderr, "   -L: local codepage\n");
 #endif
 	fprintf(stderr, "   -A: enable SeamlessRDP mode\n");
+	fprintf(stderr, "   -M: SeamlessRDP master mode socket path\n");
+	fprintf(stderr, "   -l: <command> <control socket path>: SeamlessRDP slave mode\n");
 	fprintf(stderr, "   -B: use BackingStore of X-server (if available)\n");
 	fprintf(stderr, "   -e: disable encryption (French TS)\n");
 	fprintf(stderr, "   -E: disable encryption from client to server\n");
@@ -443,6 +457,8 @@
 
 	g_num_devices = 0;
 
+	slave_cmdline = NULL;
+
 #ifdef RDP2VNC
 #define VNCOPT "V:Q:"
 #else
@@ -450,7 +466,7 @@
 #endif
 
 	while ((c = getopt(argc, argv,
-			   VNCOPT "Au:L:d:s:c:p:n:k:g:fbBeEmzCDKS:T:NX:a:x:Pr:045h?")) != -1)
+			   VNCOPT "Au:L:d:s:c:p:n:k:g:fbBeEmzCDKS:T:NX:a:x:Pr:045M:l:h?")) != -1)
 	{
 		switch (c)
 		{
@@ -783,6 +799,16 @@
 				g_use_rdp5 = True;
 				break;
 
+			case 'M':
+				master_socket = xmalloc(sizeof(char) * (strlen(optarg) + 1));
+				STRNCPY(master_socket, optarg, sizeof(char) * (strlen(optarg) + 1));
+				break;
+
+			case 'l':
+				slave_cmdline = xmalloc(sizeof(char) * (strlen(optarg) + 1));
+				STRNCPY(slave_cmdline, optarg, sizeof(char) * (strlen(optarg) + 1));
+				break;
+
 			case 'h':
 			case '?':
 			default:
@@ -800,6 +826,15 @@
 	STRNCPY(server, argv[optind], sizeof(server));
 	parse_server_and_port(server);
 
+	/* If slave mode is being used, the 'server' variable contains the name
+	 * of the control socket to use. */
+	if (slave_cmdline != NULL)
+	{
+		seamless_socket_send(server, slave_cmdline);
+		xfree(slave_cmdline);
+		return 0;
+	}
+
 	if (g_seamless_rdp)
 	{
 		if (g_win_button_size)
@@ -837,6 +872,10 @@
 		g_grab_keyboard = False;
 	}
 
+	/* If we're in master mode, create a socket and listen on it. */
+	if (master_socket != NULL)
+		seamless_create_socket(master_socket);
+
 	if (!username_option)
 	{
 		pw = getpwuid(getuid());
@@ -980,6 +1019,12 @@
 
 	cache_save_state();
 	ui_deinit();
+	/* If we opened a socket, clean it up. */
+	if (master_socket != NULL)
+	{
+		seamless_close_socket(master_socket);
+		xfree(master_socket);
+	}
 
 	if (ext_disc_reason >= 2)
 		print_disconnect_reason(ext_disc_reason);
@@ -1624,3 +1669,10 @@
 		return False;
 	return True;
 }
+
+// Send message to rdesktop running in SeamlessrRDP master mode
+void
+send_seamless_slave_message(char *cmdline)
+{
+	fprintf(stderr, cmdline);
+}
diff -Naur rdesktop/rdp.c rdesktop-modified/rdp.c
--- rdesktop/rdp.c	2006-11-02 05:38:40.000000000 +1100
+++ rdesktop-modified/rdp.c	2006-12-18 01:16:45.000000000 +1100
@@ -22,6 +22,7 @@
 #include <errno.h>
 #include <unistd.h>
 #include "rdesktop.h"
+#include "seamless.h"
 
 #ifdef HAVE_ICONV
 #ifdef HAVE_ICONV_H
@@ -51,6 +52,9 @@
 extern BOOL g_bitmap_cache_persist_enable;
 extern BOOL g_numlock_sync;
 
+/* SeamlessRDP master mode socket */
+extern char *master_socket;
+
 uint8 *g_next_packet;
 uint32 g_rdp_shareid;
 
@@ -74,6 +78,7 @@
 static BOOL g_iconv_works = True;
 #endif
 
+
 /* Receive an RDP packet */
 static STREAM
 rdp_recv(uint8 * type)
@@ -1361,7 +1366,10 @@
 rdp_main_loop(BOOL * deactivated, uint32 * ext_disc_reason)
 {
 	while (rdp_loop(deactivated, ext_disc_reason))
-		;
+	{
+		if (master_socket != NULL)
+			seamless_check_socket();
+	}
 }
 
 /* used in uiports and rdp_main_loop, processes the rdp packets waiting */
diff -Naur rdesktop/seamless.c rdesktop-modified/seamless.c
--- rdesktop/seamless.c	2006-04-28 17:55:36.000000000 +1000
+++ rdesktop-modified/seamless.c	2006-12-18 01:16:45.000000000 +1100
@@ -21,6 +21,11 @@
 #include "rdesktop.h"
 #include <stdarg.h>
 #include <assert.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <unistd.h>
+#include "seamless.h"
 
 /* #define WITH_DEBUG_SEAMLESS */
 
@@ -30,6 +35,9 @@
 #define DEBUG_SEAMLESS(args)
 #endif
 
+// Control socket file descriptor
+int sock;
+
 extern BOOL g_seamless_rdp;
 static VCHANNEL *seamless_channel;
 static unsigned int seamless_serial;
@@ -442,7 +450,6 @@
 }
 
 
-
 unsigned int
 seamless_send_focus(unsigned long id, unsigned long flags)
 {
@@ -451,3 +458,150 @@
 
 	return seamless_send("FOCUS", "0x%08lx,0x%lx", id, flags);
 }
+
+/* Send client-to-server message to spawn a new process on the server. */
+unsigned int
+seamless_send_spawn(char *cmdline)
+{
+	if (!g_seamless_rdp)
+		return (unsigned int) -1;
+
+	return seamless_send("SPAWN", cmdline);
+}
+
+
+/* Check seamless master mode socket and send spawn command if input found.
+ * Returns 0 if a slave connected and sent command, 1 otherwise.  */
+int
+seamless_check_socket()
+{
+	fd_set rfds;
+	struct timeval tv;
+	int slaves, index, ns;
+	struct sockaddr_un fsaun;
+	char cmdline[256];
+	socklen_t fromlen;
+	FILE *fp;
+	char c;
+
+	FD_ZERO(&rfds);
+	FD_SET(sock, &rfds);
+
+	/* Don't wait - set timeout to zero. */
+	tv.tv_sec = 0;
+	tv.tv_usec = 0;
+
+	/* See if any slaves are trying to connect. */
+	slaves = select(sock + 1, &rfds, NULL, NULL, &tv);
+
+	if (slaves == -1)
+	{
+		perror("Error checking socket: select()");
+		return 1;
+	}
+	/* Return if no waiting slaves */
+	else if (slaves == 0)
+	{
+		return 1;
+	}
+
+	/* Accept connection */
+	fromlen = sizeof(fsaun);
+	if ((ns = accept(sock, (struct sockaddr *) &fsaun, &fromlen)) < 0)
+	{
+		perror("server: accept");
+		exit(1);
+	}
+
+	/* Read command from client socket */
+	fp = fdopen(ns, "r");
+	index = 0;
+	while ((c = fgetc(fp)) != EOF && index < 256)
+	{
+		cmdline[index] = c;
+
+		index++;
+	}
+	cmdline[index] = '\0';
+
+	/* Send spawn command to server-side SeamlessRDP component */
+	seamless_send_spawn(cmdline);
+
+	return 0;
+}
+
+/* Create control socket */
+void
+seamless_create_socket(char *socket_name)
+{
+	struct sockaddr_un saun;
+
+	/* Create socket */
+	if ((sock = socket(AF_UNIX, SOCK_STREAM, 0)) < 0)
+	{
+		perror("Error creating socket: socket");
+		exit(1);
+	}
+
+	/* Bind to the socket. Any older socket with the same name will be
+	 * unlinked first. */
+	memset(&saun, 0, sizeof(struct sockaddr_un));
+	saun.sun_family = AF_UNIX;
+	strncpy(saun.sun_path, socket_name, sizeof(saun.sun_path));
+	unlink(socket_name);
+	if (bind(sock, (struct sockaddr *) &saun, sizeof(struct sockaddr_un)) < 0)
+	{
+		perror("Error binding to socket: bind");
+		exit(1);
+	}
+
+	/* Listen on the socket */
+	if (listen(sock, 5) < 0)
+	{
+		perror("Error listening on socket: listen");
+		exit(1);
+	}
+}
+
+/* Close control socket */
+void
+seamless_close_socket(char *socket_name)
+{
+	close(sock);
+	unlink(socket_name);
+
+	return;
+}
+
+/* Send a command line to a master process via a socket. */
+int
+seamless_socket_send(char *socket_name, char *cmdline)
+{
+	register int s, len;
+	struct sockaddr_un saun;
+
+	/* Create socket */
+	if ((s = socket(AF_UNIX, SOCK_STREAM, 0)) < 0)
+	{
+		perror("Error creating socket: socket");
+		exit(1);
+	}
+
+	/* Connect to server */
+	saun.sun_family = AF_UNIX;
+	strcpy(saun.sun_path, socket_name);
+	len = sizeof(saun.sun_family) + strlen(saun.sun_path);
+	if (connect(s, (struct sockaddr *) &saun, len) < 0)
+	{
+		perror("Error connecting to socket: connect");
+		exit(1);
+	}
+
+	/* Send command */
+	send(s, cmdline, strlen(cmdline), 0);
+
+	/* Close socket */
+	close(s);
+
+	return 0;
+}
diff -Naur rdesktop/seamless.h rdesktop-modified/seamless.h
--- rdesktop/seamless.h	2006-03-27 18:17:33.000000000 +1000
+++ rdesktop-modified/seamless.h	2006-12-18 01:16:44.000000000 +1100
@@ -17,3 +17,12 @@
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */
+
+/* Check seamless master mode socket and send spawn command if input found. */
+int seamless_check_socket();
+/* Create control socket */
+void seamless_create_socket(char *socket_name);
+/* Close control socket */
+void seamless_close_socket(char *socket_name);
+/* Send a command line to seamless master socket. */
+int seamless_socket_send(char *socket_name, char *cmdline);