diff --git a/MMAppController.h b/MMAppController.h
index 5bcbf1ea48..680330882e 100644
--- a/MMAppController.h
+++ b/MMAppController.h
@@ -9,10 +9,15 @@
  */
 
 #import <Cocoa/Cocoa.h>
+#import "MacVim.h"
 
 
 
-@interface MMAppController : NSObject {
+@interface MMAppController : NSObject
+#if MM_USE_DO
+    <MMAppProtocol>
+#endif
+{
     NSPort          *receivePort;
     NSMutableArray  *vimControllers;
     unsigned        terminateNowCount;
diff --git a/MMAppController.m b/MMAppController.m
index 08c1e9c199..83bfe49afb 100644
--- a/MMAppController.m
+++ b/MMAppController.m
@@ -10,7 +10,6 @@
 
 #import "MMAppController.h"
 #import "MMVimController.h"
-#import "MacVim.h"
 
 
 
@@ -21,6 +20,20 @@
     if ((self = [super init])) {
         vimControllers = [NSMutableArray new];
 
+#if MM_USE_DO
+        // NOTE!  If the name of the connection changes here it must also be
+        // updated in MMBackend.m.
+        NSConnection *connection = [NSConnection defaultConnection];
+        NSString *name = [NSString stringWithFormat:@"%@-connection",
+                 [[NSBundle mainBundle] bundleIdentifier]];
+        //NSLog(@"Registering connection with name '%@'", name);
+        if ([connection registerName:name]) {
+            [connection setRootObject:self];
+        } else {
+            NSLog(@"WARNING: Failed to register connection with name '%@'",
+                    name);
+        }
+#else
         // Init named port for VimTasks to connect to
         receivePort = [NSMachPort new];
         [receivePort setDelegate:self];
@@ -37,6 +50,7 @@
                                                              name:portName]) {
             NSLog(@"WARNING: Failed to start mach bootstrap server");
         }
+#endif
     }
 
     return self;
@@ -46,7 +60,9 @@
 {
     //NSLog(@"MMAppController dealloc");
 
+#if !MM_USE_DO
     [receivePort release];
+#endif
     [vimControllers release];
 
     [super dealloc];
@@ -86,6 +102,38 @@
 - (NSApplicationTerminateReply)applicationShouldTerminate:
     (NSApplication *)sender
 {
+#if MM_USE_DO
+    int reply = NSTerminateNow;
+    BOOL modifiedBuffers = NO;
+
+    unsigned i, count = [vimControllers count];
+    for (i = 0; i < count; ++i) {
+        MMVimController *controller = [vimControllers objectAtIndex:i];
+        id proxy = [controller backendProxy];
+        if (proxy && [proxy checkForModifiedBuffers]) {
+            modifiedBuffers = YES;
+            break;
+        }
+    }
+
+    if (modifiedBuffers) {
+        NSAlert *alert = [[NSAlert alloc] init];
+        [alert addButtonWithTitle:@"Quit"];
+        [alert addButtonWithTitle:@"Cancel"];
+        [alert setMessageText:@"Quit without saving?"];
+        [alert setInformativeText:@"There are modified buffers, "
+           " if you quit now all changes will be lost.  Quit anyway?"];
+        [alert setAlertStyle:NSWarningAlertStyle];
+
+        if ([alert runModal] != NSAlertFirstButtonReturn) {
+            reply = NSTerminateCancel;
+        }
+
+        [alert release];
+    }
+
+    return reply;
+#else
     int reply = NSTerminateNow;
 
     // HACK!  Send message to all vim tasks asking if they have modified
@@ -136,6 +184,7 @@
     }
 
     return reply;
+#endif
 }
 
 - (void)applicationWillTerminate:(NSNotification *)aNotification
@@ -145,6 +194,7 @@
     [self autorelease];
 }
 
+#if !MM_USE_DO
 - (void)handlePortMessage:(NSPortMessage *)portMessage
 {
     unsigned msgid = [portMessage msgid];
@@ -163,6 +213,7 @@
         NSLog(@"WARNING: Unknown message received (msgid=%d)", msgid);
     }
 }
+#endif
 
 - (void)removeVimController:(id)controller
 {
@@ -179,4 +230,22 @@
     [NSTask launchedTaskWithLaunchPath:path arguments:args];
 }
 
+#if MM_USE_DO
+- (byref id <MMFrontendProtocol>)connectBackend:
+    (byref in id <MMBackendProtocol>)backend;
+{
+    //NSLog(@"Frontend got connection request from backend...adding new "
+    //        "MMVimController");
+
+    [(NSDistantObject*)backend
+            setProtocolForProxy:@protocol(MMBackendProtocol)];
+
+    MMVimController *wc = [[[MMVimController alloc] initWithBackend:backend]
+            autorelease];
+    [vimControllers addObject:wc];
+
+    return wc;
+}
+#endif
+
 @end
diff --git a/MMBackend.h b/MMBackend.h
index 5f2aa7265d..5e28c6b525 100644
--- a/MMBackend.h
+++ b/MMBackend.h
@@ -9,15 +9,25 @@
  */
 
 #import <Foundation/Foundation.h>
+#import "MacVim.h"
 
 
 
-@interface MMBackend : NSObject {
+@interface MMBackend : NSObject
+#if MM_USE_DO
+    <MMBackendProtocol>
+#endif
+{
     NSMutableArray  *queue;
     NSMutableData   *drawData;
-    NSData          *replyData;
+#if MM_USE_DO
+    NSConnection    *connection;
+    id              frontendProxy;
+#else
     NSPort          *sendPort;
     NSPort          *receivePort;
+    NSData          *replyData;
+#endif
     NSDictionary    *colorDict;
     BOOL            inputReceived;
     BOOL            receivedKillTaskMsg;
diff --git a/MMBackend.m b/MMBackend.m
index 50c809f39b..2456ff1d4b 100644
--- a/MMBackend.m
+++ b/MMBackend.m
@@ -9,7 +9,6 @@
  */
 
 #import "MMBackend.h"
-#import "MacVim.h"
 #import "vim.h"
 
 
@@ -21,9 +20,13 @@ static int eventButtonNumberToVimMouseButton(int buttonNumber);
 
 
 @interface MMBackend (Private)
+- (void)handleMessage:(int)msgid data:(NSData *)data;
 + (NSDictionary *)specialKeys;
 - (void)handleKeyDown:(NSString *)key modifiers:(int)mods;
 - (void)queueMessage:(int)msgid data:(NSData *)data;
+#if MM_USE_DO
+- (void)connectionDidDie:(NSNotification *)notification;
+#endif
 @end
 
 
@@ -51,10 +54,17 @@ static int eventButtonNumberToVimMouseButton(int buttonNumber);
 
 - (void)dealloc
 {
+    [[NSNotificationCenter defaultCenter] removeObserver:self];
+
     [queue release];
     [drawData release];
+#if MM_USE_DO
+    [frontendProxy release];
+    [connection release];
+#else
     [sendPort release];
     [receivePort release];
+#endif
     [colorDict release];
 
     [super dealloc];
@@ -78,6 +88,14 @@ static int eventButtonNumberToVimMouseButton(int buttonNumber);
 
 - (BOOL)checkin
 {
+#if MM_USE_DO
+    // NOTE!  If the name of the connection changes here it must also be
+    // updated in MMAppController.m.
+    NSString *name = [NSString stringWithFormat:@"%@-connection",
+             [[NSBundle mainBundle] bundleIdentifier]];
+    connection = [NSConnection connectionWithRegisteredName:name host:nil];
+    if (!connection)
+#else
     // NOTE!  If the name of the port changes here it must also be updated in
     // MMAppController.m.
     NSString *portName = [NSString stringWithFormat:@"%@-taskport",
@@ -85,7 +103,9 @@ static int eventButtonNumberToVimMouseButton(int buttonNumber);
 
     NSPort *port = [[[NSMachBootstrapServer sharedInstance]
             portForName:portName host:nil] retain];
-    if (!port) {
+    if (!port)
+#endif
+    {
 #if 0
         NSString *path = [[NSBundle mainBundle] bundlePath];
         if (![[NSWorkspace sharedWorkspace] launchApplication:path]) {
@@ -113,20 +133,52 @@ static int eventButtonNumberToVimMouseButton(int buttonNumber);
         // returns a valid port.  Also set a time-out date so that we don't get
         // stuck doing this forever.
         NSDate *timeOutDate = [NSDate dateWithTimeIntervalSinceNow:15];
-        while (!port &&
-                NSOrderedDescending == [timeOutDate compare:[NSDate date]]) {
+        while (
+#if MM_USE_DO
+                !connection
+#else
+                !port
+#endif
+                && NSOrderedDescending == [timeOutDate compare:[NSDate date]])
+        {
             [[NSRunLoop currentRunLoop]
                     runMode:NSDefaultRunLoopMode
                  beforeDate:[NSDate dateWithTimeIntervalSinceNow:1]];
-            port = [[NSMachBootstrapServer sharedInstance] portForName:portName];
+#if MM_USE_DO
+            connection = [NSConnection connectionWithRegisteredName:name
+                                                               host:nil];
+#else
+            port = [[NSMachBootstrapServer sharedInstance]
+                    portForName:portName];
+#endif
         }
 
-        if (!port) {
+#if MM_USE_DO
+        if (!connection)
+#else
+        if (!port)
+#endif
+        {
             NSLog(@"WARNING: Timed-out waiting for GUI to launch.");
             return NO;
         }
     }
 
+#if MM_USE_DO
+    id proxy = [connection rootProxy];
+    [proxy setProtocolForProxy:@protocol(MMAppProtocol)];
+
+    [[NSNotificationCenter defaultCenter] addObserver:self
+            selector:@selector(connectionDidDie:)
+                name:NSConnectionDidDieNotification object:connection];
+
+    frontendProxy = [(NSDistantObject*)[proxy connectBackend:self] retain];
+    if (frontendProxy) {
+        [frontendProxy setProtocolForProxy:@protocol(MMAppProtocol)];
+    }
+
+    return connection && frontendProxy;
+#else
     receivePort = [NSMachPort new];
     [receivePort setDelegate:self];
 
@@ -137,10 +189,12 @@ static int eventButtonNumberToVimMouseButton(int buttonNumber);
                    receivePort:receivePort wait:YES];
 
     return YES;
+#endif
 }
 
 - (BOOL)openVimWindowWithRows:(int)rows columns:(int)cols
 {
+#if !MM_USE_DO
     if (!sendPort) {
 #if 0
         // TODO: Wait until connected---maybe time out at some point?
@@ -165,6 +219,7 @@ static int eventButtonNumberToVimMouseButton(int buttonNumber);
         }
 #endif
     }
+#endif // !MM_USE_DO
 
     NSMutableData *data = [NSMutableData data];
 
@@ -276,19 +331,25 @@ static int eventButtonNumberToVimMouseButton(int buttonNumber);
         // TODO: Come up with a better way to handle the insertion point.
         [self updateInsertionPoint];
 
+#if MM_USE_DO
+        [frontendProxy processCommandQueue:queue];
+#else
         [NSPortMessage sendMessage:FlushQueueMsgID withSendPort:sendPort
                               components:queue wait:YES];
+#endif
         [queue removeAllObjects];
     }
 }
 
 - (BOOL)waitForInput:(int)milliseconds
 {
+#if !MM_USE_DO
     if (![receivePort isValid]) {
         // This should only happen if the GUI crashes.
         NSLog(@"ERROR: The receive port is no longer valid, quitting...");
         getout(0);
     }
+#endif
 
     NSDate *date = milliseconds > 0 ?
             [NSDate dateWithTimeIntervalSinceNow:.001*milliseconds] : 
@@ -308,10 +369,18 @@ static int eventButtonNumberToVimMouseButton(int buttonNumber);
 
 - (void)exit
 {
+#if MM_USE_DO
+    // By invalidating the NSConnection the MMWindowController immediately
+    // finds out that the connection is down and as a result
+    // [MMWindowController connectionDidDie:] is invoked.
+    [[NSNotificationCenter defaultCenter] removeObserver:self];
+    [connection invalidate];
+#else
     if (!receivedKillTaskMsg) {
         [NSPortMessage sendMessage:TaskExitedMsgID withSendPort:sendPort
                        receivePort:receivePort wait:YES];
     }
+#endif
 }
 
 - (void)selectTab:(int)index
@@ -388,6 +457,9 @@ static int eventButtonNumberToVimMouseButton(int buttonNumber);
 - (char *)browseForFileInDirectory:(char *)dir title:(char *)title
                             saving:(int)saving
 {
+#if MM_USE_DO
+    return nil;
+#else
     //NSLog(@"browseForFileInDirectory:%s title:%s saving:%d", dir, title,
     //        saving);
 
@@ -430,6 +502,7 @@ static int eventButtonNumberToVimMouseButton(int buttonNumber);
 
     [replyData release];  replyData = nil;
     return (char*)s;
+#endif // MM_USE_DO
 }
 
 - (void)updateInsertionPoint
@@ -665,6 +738,27 @@ static int eventButtonNumberToVimMouseButton(int buttonNumber);
     return INVALCOLOR;
 }
 
+#if MM_USE_DO
+- (oneway void)processInput:(int)msgid data:(in NSData *)data
+{
+    [self handleMessage:msgid data:data];
+    inputReceived = YES;
+}
+
+- (BOOL)checkForModifiedBuffers
+{
+    buf_T *buf;
+    for (buf = firstbuf; buf != NULL; buf = buf->b_next) {
+        if (bufIsChanged(buf)) {
+            return YES;
+        }
+    }
+
+    return NO;
+}
+
+#else // MM_USE_DO
+
 - (void)handlePortMessage:(NSPortMessage *)portMessage
 {
     unsigned msgid = [portMessage msgid];
@@ -672,17 +766,48 @@ static int eventButtonNumberToVimMouseButton(int buttonNumber);
     if (ConnectedMsgID == msgid) {
         sendPort = [[portMessage sendPort] retain];
         //NSLog(@"VimTask connected to MMVimController.");
-    } else if (KillTaskMsgID == msgid) {
+    } else if (TaskShouldTerminateMsgID == msgid) {
+        int reply = TerminateReplyYesMsgID;
+        buf_T *buf;
+        for (buf = firstbuf; buf != NULL; buf = buf->b_next) {
+            if (bufIsChanged(buf)) {
+                reply = TerminateReplyNoMsgID;
+                break;
+            }
+        }
+
+        //NSLog(@"TaskShouldTerminateMsgID = %s",
+        //        reply == TerminateReplyYesMsgID ? "YES" : "NO");
+
+        [NSPortMessage sendMessage:reply withSendPort:[portMessage sendPort]
+                              wait:YES];
+    } else {
+        NSArray *components = [portMessage components];
+        NSData *data = [components count] > 0 ?
+                [components objectAtIndex:0] : nil;
+        [self handleMessage:msgid data:data];
+    }
+}
+#endif // MM_USE_DO
+
+@end // MMBackend
+
+
+
+@implementation MMBackend (Private)
+
+- (void)handleMessage:(int)msgid data:(NSData *)data
+{
+    if (KillTaskMsgID == msgid) {
         //NSLog(@"VimTask received kill message; exiting now.");
         // Set this flag here so that exit does not send TaskExitedMsgID back
         // to MMVimController.
         receivedKillTaskMsg = YES;
         getout(0);
     } else if (InsertTextMsgID == msgid) {
-        if (![[portMessage components] count]) return;
-        NSString *key = [[NSString alloc]
-                initWithData:[[portMessage components] objectAtIndex:0]
-                    encoding:NSUTF8StringEncoding];
+        if (!data) return;
+        NSString *key = [[NSString alloc] initWithData:data
+                                              encoding:NSUTF8StringEncoding];
         //NSLog(@"insert text: %@  (hex=%x)", key, [key characterAtIndex:0]);
         add_to_input_buf((char_u*)[key UTF8String],
                 [key lengthOfBytesUsingEncoding:NSUTF8StringEncoding]);
@@ -690,8 +815,8 @@ static int eventButtonNumberToVimMouseButton(int buttonNumber);
 
         inputReceived = YES;
     } else if (KeyDownMsgID == msgid || CmdKeyMsgID == msgid) {
-        if (![[portMessage components] count]) return;
-        const void *bytes = [[[portMessage components] objectAtIndex:0] bytes];
+        if (!data) return;
+        const void *bytes = [data bytes];
         int mods = *((int*)bytes);  bytes += sizeof(int);
         int len = *((int*)bytes);  bytes += sizeof(int);
         NSString *key = [[NSString alloc] initWithBytes:bytes length:len
@@ -703,15 +828,15 @@ static int eventButtonNumberToVimMouseButton(int buttonNumber);
         [key release];
         inputReceived = YES;
     } else if (SelectTabMsgID == msgid) {
-        if (![[portMessage components] count]) return;
-        const void *bytes = [[[portMessage components] objectAtIndex:0] bytes];
+        if (!data) return;
+        const void *bytes = [data bytes];
         int idx = *((int*)bytes) + 1;
         //NSLog(@"Selecting tab %d", idx);
         send_tabline_event(idx);
         inputReceived = YES;
     } else if (CloseTabMsgID == msgid) {
-        if (![[portMessage components] count]) return;
-        const void *bytes = [[[portMessage components] objectAtIndex:0] bytes];
+        if (!data) return;
+        const void *bytes = [data bytes];
         int idx = *((int*)bytes) + 1;
         //NSLog(@"Closing tab %d", idx);
         send_tabline_menu_event(idx, TABLINE_MENU_CLOSE);
@@ -721,8 +846,8 @@ static int eventButtonNumberToVimMouseButton(int buttonNumber);
         send_tabline_menu_event(0, TABLINE_MENU_NEW);
         inputReceived = YES;
     } else if (DraggedTabMsgID == msgid) {
-        if (![[portMessage components] count]) return;
-        const void *bytes = [[[portMessage components] objectAtIndex:0] bytes];
+        if (!data) return;
+        const void *bytes = [data bytes];
         // NOTE! The destination index is 0 based, so do not add 1 to make it 1
         // based.
         int idx = *((int*)bytes);
@@ -743,8 +868,8 @@ static int eventButtonNumberToVimMouseButton(int buttonNumber);
         tabpage_move(idx);
 #endif
     } else if (ScrollWheelMsgID == msgid) {
-        if (![[portMessage components] count]) return;
-        const void *bytes = [[[portMessage components] objectAtIndex:0] bytes];
+        if (!data) return;
+        const void *bytes = [data bytes];
 
         int row = *((int*)bytes);  bytes += sizeof(int);
         int col = *((int*)bytes);  bytes += sizeof(int);
@@ -759,8 +884,8 @@ static int eventButtonNumberToVimMouseButton(int buttonNumber);
         gui_send_mouse_event(button, col, row, NO, flags);
         inputReceived = YES;
     } else if (MouseDownMsgID == msgid) {
-        if (![[portMessage components] count]) return;
-        const void *bytes = [[[portMessage components] objectAtIndex:0] bytes];
+        if (!data) return;
+        const void *bytes = [data bytes];
 
         int row = *((int*)bytes);  bytes += sizeof(int);
         int col = *((int*)bytes);  bytes += sizeof(int);
@@ -775,8 +900,8 @@ static int eventButtonNumberToVimMouseButton(int buttonNumber);
 
         inputReceived = YES;
     } else if (MouseUpMsgID == msgid) {
-        if (![[portMessage components] count]) return;
-        const void *bytes = [[[portMessage components] objectAtIndex:0] bytes];
+        if (!data) return;
+        const void *bytes = [data bytes];
 
         int row = *((int*)bytes);  bytes += sizeof(int);
         int col = *((int*)bytes);  bytes += sizeof(int);
@@ -787,8 +912,8 @@ static int eventButtonNumberToVimMouseButton(int buttonNumber);
         gui_send_mouse_event(MOUSE_RELEASE, col, row, NO, flags);
         inputReceived = YES;
     } else if (MouseDraggedMsgID == msgid) {
-        if (![[portMessage components] count]) return;
-        const void *bytes = [[[portMessage components] objectAtIndex:0] bytes];
+        if (!data) return;
+        const void *bytes = [data bytes];
 
         int row = *((int*)bytes);  bytes += sizeof(int);
         int col = *((int*)bytes);  bytes += sizeof(int);
@@ -798,21 +923,25 @@ static int eventButtonNumberToVimMouseButton(int buttonNumber);
 
         gui_send_mouse_event(MOUSE_DRAG, col, row, NO, flags);
         inputReceived = YES;
-    } else if (BrowseForFileReplyMsgID == msgid) {
-        if (![[portMessage components] count]) return;
+    } 
+#if !MM_USE_DO
+    else if (BrowseForFileReplyMsgID == msgid) {
+        if (!data) return;
         [replyData release];
-        replyData = [[[portMessage components] objectAtIndex:0] copy];
-    } else if (SetTextDimensionsMsgID == msgid) {
-        if (![[portMessage components] count]) return;
-        const void *bytes = [[[portMessage components] objectAtIndex:0] bytes];
+        replyData = [data copy];
+    }
+#endif
+    else if (SetTextDimensionsMsgID == msgid) {
+        if (!data) return;
+        const void *bytes = [data bytes];
         int rows = *((int*)bytes);  bytes += sizeof(int);
         int cols = *((int*)bytes);  bytes += sizeof(int);
 
         //NSLog(@"[VimTask] Resizing shell to %dx%d.", cols, rows);
         gui_resize_shell(cols, rows);
     } else if (ExecuteMenuMsgID == msgid) {
-        if (![[portMessage components] count]) return;
-        const void *bytes = [[[portMessage components] objectAtIndex:0] bytes];
+        if (!data) return;
+        const void *bytes = [data bytes];
         int tag = *((int*)bytes);  bytes += sizeof(int);
 
         vimmenu_T *menu = (vimmenu_T*)tag;
@@ -821,24 +950,9 @@ static int eventButtonNumberToVimMouseButton(int buttonNumber);
             gui_menu_cb(menu);
             inputReceived = YES;
         }
-    } else if (TaskShouldTerminateMsgID == msgid) {
-        int reply = TerminateReplyYesMsgID;
-        buf_T *buf;
-        for (buf = firstbuf; buf != NULL; buf = buf->b_next) {
-            if (bufIsChanged(buf)) {
-                reply = TerminateReplyNoMsgID;
-                break;
-            }
-        }
-
-        //NSLog(@"TaskShouldTerminateMsgID = %s",
-        //        reply == TerminateReplyYesMsgID ? "YES" : "NO");
-
-        [NSPortMessage sendMessage:reply withSendPort:[portMessage sendPort]
-                              wait:YES];
     } else if (ScrollbarEventMsgID == msgid) {
-        if (![[portMessage components] count]) return;
-        const void *bytes = [[[portMessage components] objectAtIndex:0] bytes];
+        if (!data) return;
+        const void *bytes = [data bytes];
         long ident = *((long*)bytes);  bytes += sizeof(long);
         int hitPart = *((int*)bytes);  bytes += sizeof(int);
         float fval = *((float*)bytes);  bytes += sizeof(float);
@@ -900,18 +1014,13 @@ static int eventButtonNumberToVimMouseButton(int buttonNumber);
 
             inputReceived = YES;
         }
+    } else if (VimShouldCloseMsgID == msgid) {
+        gui_shell_closed();
     } else {
         NSLog(@"WARNING: Unknown message received (msgid=%d)", msgid);
     }
 }
 
-
-@end // MMBackend
-
-
-
-@implementation MMBackend (Private)
-
 + (NSDictionary *)specialKeys
 {
     static NSDictionary *specialKeys = nil;
@@ -1002,6 +1111,19 @@ static int eventButtonNumberToVimMouseButton(int buttonNumber);
         [queue addObject:[NSData data]];
 }
 
+#if MM_USE_DO
+- (void)connectionDidDie:(NSNotification *)notification
+{
+    // If the main connection to MacVim is lost this means that MacVim was
+    // either quit (by the user chosing Quit on the MacVim menu), or it has
+    // crashed.  In either case our only option is to quit now.
+    // TODO: Write backup file?
+
+    //NSLog(@"A Vim process lots its connection to MacVim; quitting.");
+    getout(0);
+}
+#endif // MM_USE_DO
+
 @end // MMBackend (Private)
 
 
diff --git a/MMTextStorage.m b/MMTextStorage.m
index d4fd08ac72..13315018ef 100644
--- a/MMTextStorage.m
+++ b/MMTextStorage.m
@@ -54,6 +54,8 @@
 
 - (void)dealloc
 {
+    //NSLog(@"%@ %s", [self className], _cmd);
+
     [emptyRowString release];
     //[paragraphStyle release];
     [font release];
diff --git a/MMTextView.h b/MMTextView.h
index 04905f1d26..6acdb8843b 100644
--- a/MMTextView.h
+++ b/MMTextView.h
@@ -12,15 +12,9 @@
 
 
 @interface MMTextView : NSTextView {
-    BOOL    ownsTextStorage;
-    int     tabpageIdx;
-    NSPort  *sendPort;
     BOOL    shouldDrawInsertionPoint;
 }
 
-- (id)initWithPort:(NSPort *)port frame:(NSRect)frame
-     textContainer:(NSTextContainer *)tc;
-- (MMTextView *)initWithFrame:(NSRect)frame port:(NSPort *)port;
 - (void)setShouldDrawInsertionPoint:(BOOL)enable;
 
 @end
diff --git a/MMTextView.m b/MMTextView.m
index 4c990489fa..fbe3990c77 100644
--- a/MMTextView.m
+++ b/MMTextView.m
@@ -10,80 +10,22 @@
 
 #import "MMTextView.h"
 #import "MMTextStorage.h"
-#import "MacVim.h"
 #import "MMWindowController.h"
+#import "MMVimController.h"
+#import "MacVim.h"
 
 
 
 @interface MMTextView (Private)
 - (BOOL)convertPoint:(NSPoint)point toRow:(int *)row column:(int *)column;
 - (void)dispatchKeyEvent:(NSEvent *)event;
+- (MMVimController *)vimController;
 @end
 
 
 
 @implementation MMTextView
 
-- (id)initWithPort:(NSPort *)port frame:(NSRect)frame
-     textContainer:(NSTextContainer *)tc
-{
-    if ((self = [super initWithFrame:frame textContainer:tc])) {
-        sendPort = [port retain];
-    }
-
-    return self;
-}
-
-- (MMTextView *)initWithFrame:(NSRect)frame port:(NSPort *)port
-{
-    MMTextStorage *ts = [[MMTextStorage alloc] init];
-    NSLayoutManager *lm = [[NSLayoutManager alloc] init];
-    NSTextContainer *tc = [[NSTextContainer alloc] initWithContainerSize:
-            NSMakeSize(1.0e7,1.0e7)];
-
-    [tc setWidthTracksTextView:NO];
-    [tc setHeightTracksTextView:NO];
-    [tc setLineFragmentPadding:0];
-
-    [ts addLayoutManager:lm];
-    [lm addTextContainer:tc];
-
-    [tc release];
-    [lm release];
-
-    // HACK! Where should i get these values from?
-    // TODO: get values from frame
-    [ts setMaxRows:24 columns:80];
-
-    if ((self = [super initWithFrame:frame textContainer:tc])) {
-        ownsTextStorage = YES;
-        //[self setRichText:NO];
-        sendPort = [port retain];
-    } else {
-        ownsTextStorage = NO;
-        [ts release];
-    }
-
-    return self;
-}
-
-
-- (void)dealloc
-{
-    // BUG!  The reference count of the text view will never reach 0 unless
-    // release is explicitly called on the text storage;  so this code is
-    // meaningless.
-    if (ownsTextStorage) {
-        [[self textContainer] setTextView:nil];
-        [[self textStorage] release];
-        ownsTextStorage = NO;
-    }
-
-    [sendPort release];
-
-    [super dealloc];
-}
-
 - (void)setShouldDrawInsertionPoint:(BOOL)enable
 {
     shouldDrawInsertionPoint = enable;
@@ -122,9 +64,9 @@
 
     [NSCursor setHiddenUntilMouseMoves:YES];
 
-    [NSPortMessage sendMessage:InsertTextMsgID withSendPort:sendPort
-                          data:[string dataUsingEncoding:NSUTF8StringEncoding]
-                          wait:NO];
+    [[self vimController] sendMessage:InsertTextMsgID
+                 data:[string dataUsingEncoding:NSUTF8StringEncoding]
+                 wait:NO];
 }
 
 
@@ -174,8 +116,7 @@
     [data appendBytes:&len length:sizeof(int)];
     [data appendBytes:[string UTF8String] length:len];
 
-    [NSPortMessage sendMessage:CmdKeyMsgID withSendPort:sendPort data:data
-                          wait:NO];
+    [[self vimController] sendMessage:CmdKeyMsgID data:data wait:NO];
 
     return YES;
 }
@@ -220,8 +161,7 @@
     [data appendBytes:&flags length:sizeof(int)];
     [data appendBytes:&dy length:sizeof(float)];
 
-    [NSPortMessage sendMessage:ScrollWheelMsgID withSendPort:sendPort
-                          data:data wait:NO];
+    [[self vimController] sendMessage:ScrollWheelMsgID data:data wait:NO];
 }
 
 - (void)mouseDown:(NSEvent *)event
@@ -242,8 +182,7 @@
     [data appendBytes:&flags length:sizeof(int)];
     [data appendBytes:&count length:sizeof(int)];
 
-    [NSPortMessage sendMessage:MouseDownMsgID withSendPort:sendPort
-                          data:data wait:NO];
+    [[self vimController] sendMessage:MouseDownMsgID data:data wait:NO];
 }
 
 - (void)rightMouseDown:(NSEvent *)event
@@ -270,8 +209,7 @@
     [data appendBytes:&col length:sizeof(int)];
     [data appendBytes:&flags length:sizeof(int)];
 
-    [NSPortMessage sendMessage:MouseUpMsgID withSendPort:sendPort
-                          data:data wait:NO];
+    [[self vimController] sendMessage:MouseUpMsgID data:data wait:NO];
 }
 
 - (void)rightMouseUp:(NSEvent *)event
@@ -298,8 +236,7 @@
     [data appendBytes:&col length:sizeof(int)];
     [data appendBytes:&flags length:sizeof(int)];
 
-    [NSPortMessage sendMessage:MouseDraggedMsgID withSendPort:sendPort
-                          data:data wait:NO];
+    [[self vimController] sendMessage:MouseDraggedMsgID data:data wait:NO];
 }
 
 - (void)rightMouseDragged:(NSEvent *)event
@@ -393,9 +330,17 @@
 
         [NSCursor setHiddenUntilMouseMoves:YES];
 
-        [NSPortMessage sendMessage:KeyDownMsgID withSendPort:sendPort data:data
-                              wait:NO];
+        [[self vimController] sendMessage:KeyDownMsgID data:data wait:NO];
     }
 }
 
+- (MMVimController *)vimController
+{
+    id windowController = [[self window] windowController];
+
+    // TODO: Make sure 'windowController' is a MMWindowController before type
+    // casting.
+    return [(MMWindowController*)windowController vimController];
+}
+
 @end // MMTextView (Private)
diff --git a/MMVimController.h b/MMVimController.h
index 19da37f264..5917d474ff 100644
--- a/MMVimController.h
+++ b/MMVimController.h
@@ -9,15 +9,24 @@
  */
 
 #import <Cocoa/Cocoa.h>
+#import "MacVim.h"
 
 @class MMWindowController;
 
 
 
-@interface MMVimController : NSObject {
+@interface MMVimController : NSObject
+#if MM_USE_DO
+    <MMFrontendProtocol>
+#endif
+{
     MMWindowController  *windowController;
+#if MM_USE_DO
+    id                  backendProxy;
+#else
     NSPort              *sendPort;
     NSPort              *receivePort;
+#endif
     NSMutableArray      *mainMenuItems;
     BOOL                shouldUpdateMainMenu;
     //NSMutableArray      *popupMenus;
@@ -25,9 +34,15 @@
     NSMutableDictionary *toolbarItemDict;
 }
 
+#if MM_USE_DO
+- (id)initWithBackend:(id)backend;
+- (id)backendProxy;
+#else
 - (id)initWithPort:(NSPort *)port;
-- (void)windowWillClose:(NSNotification *)notification;
 - (NSPort *)sendPort;
+#endif
+- (void)windowWillClose:(NSNotification *)notification;
+- (void)sendMessage:(int)msgid data:(NSData *)data wait:(BOOL)wait;
 
 @end
 
diff --git a/MMVimController.m b/MMVimController.m
index cd7e44451c..54045efb19 100644
--- a/MMVimController.m
+++ b/MMVimController.m
@@ -10,7 +10,6 @@
 
 #import "MMVimController.h"
 #import "MMWindowController.h"
-#import "MacVim.h"
 #import "MMAppController.h"
 #import "MMTextView.h"
 #import "MMTextStorage.h"
@@ -32,6 +31,7 @@ static NSString *DefaultToolbarImageName = @"Attention";
 - (IBAction)toolbarAction:(id)sender;
 - (void)addToolbarItemToDictionaryWithTag:(int)tag label:(NSString *)title
         toolTip:(NSString *)tip icon:(NSString *)icon;
+- (void)connectionDidDie:(NSNotification *)notification;
 @end
 
 
@@ -67,10 +67,40 @@ static NSMenuItem *findMenuItemWithTagInMenu(NSMenu *root, int tag)
 
 @implementation MMVimController
 
+#if MM_USE_DO
+- (id)initWithBackend:(id)backend
+#else
 - (id)initWithPort:(NSPort *)port
+#endif
 {
     if ((self = [super init])) {
-        windowController = [[MMWindowController alloc] initWithPort:port];
+        windowController =
+            [[MMWindowController alloc] initWithVimController:self];
+#if MM_USE_DO
+        backendProxy = [backend retain];
+
+        NSConnection *connection = [backendProxy connectionForProxy];
+        [[NSNotificationCenter defaultCenter] addObserver:self
+                selector:@selector(connectionDidDie:)
+                    name:NSConnectionDidDieNotification object:connection];
+#else
+        sendPort = [port retain];
+
+        // Init receive port and send connected message to VimTask
+        receivePort = [NSMachPort new];
+        [receivePort setDelegate:self];
+
+        // Add to the default run loop mode as well as the event tracking mode;
+        // the latter ensures that updates from the VimTask reaches
+        // MMVimController whilst the user resizes a window with the mouse.
+        [[NSRunLoop currentRunLoop] addPort:receivePort
+                                    forMode:NSDefaultRunLoopMode];
+        [[NSRunLoop currentRunLoop] addPort:receivePort
+                                    forMode:NSEventTrackingRunLoopMode];
+
+        [NSPortMessage sendMessage:ConnectedMsgID withSendPort:sendPort
+                       receivePort:receivePort wait:YES];
+#endif
 
         mainMenuItems = [[NSMutableArray alloc] init];
 
@@ -90,22 +120,6 @@ static NSMenuItem *findMenuItemWithTagInMenu(NSMenu *root, int tag)
                        name:NSWindowDidBecomeMainNotification
                      object:[windowController window]];
 
-        sendPort = [port retain];
-
-        // Init receive port and send connected message to VimTask
-        receivePort = [NSMachPort new];
-        [receivePort setDelegate:self];
-
-        // Add to the default run loop mode as well as the event tracking mode;
-        // the latter ensures that updates from the VimTask reaches
-        // MMVimController whilst the user resizes a window with the mouse.
-        [[NSRunLoop currentRunLoop] addPort:receivePort
-                                    forMode:NSDefaultRunLoopMode];
-        [[NSRunLoop currentRunLoop] addPort:receivePort
-                                    forMode:NSEventTrackingRunLoopMode];
-
-        [NSPortMessage sendMessage:ConnectedMsgID withSendPort:sendPort
-                       receivePort:receivePort wait:YES];
     }
 
     return self;
@@ -113,24 +127,67 @@ static NSMenuItem *findMenuItemWithTagInMenu(NSMenu *root, int tag)
 
 - (void)dealloc
 {
+    //NSLog(@"%@ %s", [self className], _cmd);
+
+    [[NSNotificationCenter defaultCenter] removeObserver:self];
+
+#if MM_USE_DO
+    [backendProxy release];
+#else
     if (sendPort) {
         // Kill task immediately
         [NSPortMessage sendMessage:KillTaskMsgID withSendPort:sendPort
                        receivePort:receivePort wait:NO];
     }
 
-    [[NSNotificationCenter defaultCenter] removeObserver:self];
+    [sendPort release];
+    [receivePort release];
+#endif
 
     [toolbarItemDict release];
     [toolbar release];
     [mainMenuItems release];
     [windowController release];
-    [sendPort release];
-    [receivePort release];
 
     [super dealloc];
 }
 
+- (id)backendProxy
+{
+    return backendProxy;
+}
+
+- (void)sendMessage:(int)msgid data:(NSData *)data wait:(BOOL)wait
+{
+#if MM_USE_DO
+    // TODO: Decrease reply/request timeouts if 'wait' is off.
+    [backendProxy processInput:msgid data:data];
+#else
+    [NSPortMessage sendMessage:msgid withSendPort:sendPort data:data
+                          wait:wait];
+#endif
+}
+
+#if MM_USE_DO
+- (oneway void)processCommandQueue:(in NSArray *)queue
+{
+    unsigned i, count = [queue count];
+    if (count % 2) {
+        NSLog(@"WARNING: Uneven number of components (%d) in flush queue "
+                "message; ignoring this message.", count);
+        return;
+    }
+
+    for (i = 0; i < count; i += 2) {
+        NSData *value = [queue objectAtIndex:i];
+        NSData *data = [queue objectAtIndex:i+1];
+
+        [self handleMessage:*((int*)[value bytes]) data:data];
+    }
+}
+
+#else // MM_USE_DO
+
 - (NSPort *)sendPort
 {
     return sendPort;
@@ -138,6 +195,8 @@ static NSMenuItem *findMenuItemWithTagInMenu(NSMenu *root, int tag)
 
 - (void)handlePortMessage:(NSPortMessage *)portMessage
 {
+    //NSLog(@"%@ %s %@", [self className], _cmd, portMessage);
+
     NSArray *components = [portMessage components];
     unsigned msgid = [portMessage msgid];
 
@@ -168,6 +227,7 @@ static NSMenuItem *findMenuItemWithTagInMenu(NSMenu *root, int tag)
     if (shouldUpdateMainMenu)
         [self updateMainMenu];
 }
+#endif // MM_USE_DO
 
 - (void)windowWillClose:(NSNotification *)notification
 {
@@ -216,6 +276,8 @@ static NSMenuItem *findMenuItemWithTagInMenu(NSMenu *root, int tag)
 
 - (void)handleMessage:(int)msgid data:(NSData *)data
 {
+    //NSLog(@"%@ %s", [self className], _cmd);
+
     if (OpenVimWindowMsgID == msgid) {
         const void *bytes = [data bytes];
         int rows = *((int*)bytes);  bytes += sizeof(int);
@@ -225,7 +287,9 @@ static NSMenuItem *findMenuItemWithTagInMenu(NSMenu *root, int tag)
         //        cols, rows);
 
         [windowController openWindowWithRows:rows columns:cols];
-    } else if (TaskExitedMsgID == msgid) {
+    }
+#if !MM_USE_DO
+    else if (TaskExitedMsgID == msgid) {
         //NSLog(@"Received task exited message from VimTask; closing window.");
 
         // Release sendPort immediately to avoid dealloc trying to send a 'kill
@@ -237,7 +301,9 @@ static NSMenuItem *findMenuItemWithTagInMenu(NSMenu *root, int tag)
 
         // HACK! Make sure no menu updating is done, we're about to close.
         shouldUpdateMainMenu = NO;
-    } else if (BatchDrawMsgID == msgid) {
+    }
+#endif // !MM_USE_DO
+    else if (BatchDrawMsgID == msgid) {
         //NSLog(@"Received batch draw message from VimTask.");
 
         [self performBatchDrawWithData:data];
@@ -673,6 +739,7 @@ static NSMenuItem *findMenuItemWithTagInMenu(NSMenu *root, int tag)
 
 - (void)panelDidEnd:(NSSavePanel *)panel code:(int)code context:(void *)context
 {
+#if !MM_USE_DO
     NSMutableData *data = [NSMutableData data];
     int ok = (code == NSOKButton);
     NSString *filename = [panel filename];
@@ -690,6 +757,7 @@ static NSMenuItem *findMenuItemWithTagInMenu(NSMenu *root, int tag)
     }
 
     [windowController setStatusText:@""];
+#endif // !MM_USE_DO
 }
 
 - (NSMenuItem *)menuItemForTag:(int)tag
@@ -801,6 +869,15 @@ static NSMenuItem *findMenuItemWithTagInMenu(NSMenu *root, int tag)
     [item release];
 }
 
+#if MM_USE_DO
+- (void)connectionDidDie:(NSNotification *)notification
+{
+    //NSLog(@"A MMVimController lost its connection to the backend; "
+    //       "closing the controller.");
+    [windowController close];
+}
+#endif // MM_USE_DO
+
 @end // MMVimController (Private)
 
 
diff --git a/MMWindowController.h b/MMWindowController.h
index 8afa6df892..fbe82d2803 100644
--- a/MMWindowController.h
+++ b/MMWindowController.h
@@ -13,6 +13,7 @@
 @class PSMTabBarControl;
 @class MMTextView;
 @class MMTextStorage;
+@class MMVimController;
 
 
 @interface MMWindowController : NSWindowController
@@ -20,7 +21,8 @@
     IBOutlet PSMTabBarControl *tabBarControl;
     IBOutlet NSTabView *tabView;
     IBOutlet NSTextField *statusTextField;
-    NSPort *sendPort;
+
+    MMVimController *vimController;
     BOOL vimTaskSelectedTab;
     NSTimer *statusTimer;
     MMTextView *textView;
@@ -29,7 +31,8 @@
     BOOL setupDone;
 }
 
-- (id)initWithPort:(NSPort *)port;
+- (id)initWithVimController:(MMVimController *)controller;
+- (MMVimController *)vimController;
 - (MMTextView *)textView;
 - (MMTextStorage *)textStorage;
 - (void)openWindowWithRows:(int)rows columns:(int)cols;
diff --git a/MMWindowController.m b/MMWindowController.m
index fa85832de9..fdfdc23fd4 100644
--- a/MMWindowController.m
+++ b/MMWindowController.m
@@ -12,6 +12,7 @@
 #import <PSMTabBarControl.h>
 #import "MMTextView.h"
 #import "MMTextStorage.h"
+#import "MMVimController.h"
 #import "MacVim.h"
 
 
@@ -93,10 +94,10 @@ NSMutableArray *buildMenuAddress(NSMenu *menu)
 
 @implementation MMWindowController
 
-- (id)initWithPort:(NSPort *)port
+- (id)initWithVimController:(MMVimController *)controller
 {
     if ((self = [super initWithWindowNibName:@"VimWindow"])) {
-        sendPort = [port retain];
+        vimController = controller;
         scrollbars = [[NSMutableArray alloc] init];
         textStorage = [[MMTextStorage alloc] init];
     }
@@ -106,8 +107,12 @@ NSMutableArray *buildMenuAddress(NSMenu *menu)
 
 - (void)dealloc
 {
+    //NSLog(@"%@ %s", [self className], _cmd);
+
     // TODO: release tabBarControl and tabView?
 
+    vimController = nil;
+
     [tabBarControl setDelegate:nil];
     [[self window] setDelegate:nil];
 
@@ -116,11 +121,15 @@ NSMutableArray *buildMenuAddress(NSMenu *menu)
     [scrollbars release];
     [textView release];
     [textStorage release];
-    [sendPort release];
 
     [super dealloc];
 }
 
+- (MMVimController *)vimController
+{
+    return vimController;
+}
+
 - (void)windowDidLoad
 {
     // Called after window nib file is loaded.
@@ -223,39 +232,6 @@ NSMutableArray *buildMenuAddress(NSMenu *menu)
 
 - (void)openWindowWithRows:(int)rows columns:(int)cols
 {
-#if 0
-    // Make sure window nib file is loaded.
-    [self window];
-
-    // Set up text system
-    textStorage = [[MMTextStorage alloc] init];
-    NSLayoutManager *lm = [[NSLayoutManager alloc] init];
-    NSTextContainer *tc = [[NSTextContainer alloc] initWithContainerSize:
-            NSMakeSize(1.0e7,1.0e7)];
-
-    [tc setWidthTracksTextView:NO];
-    [tc setHeightTracksTextView:NO];
-    [tc setLineFragmentPadding:0];
-
-    [textStorage setMaxRows:rows columns:cols];
-    [textStorage addLayoutManager:lm];
-    [lm addTextContainer:tc];
-    //[[lm typesetter] setUsesFontLeading:NO];
-
-    textView = [[MMTextView alloc] initWithPort:sendPort frame:[tabView frame]
-                                textContainer:tc];
-    [[self window] makeFirstResponder:textView];
-
-    // Keep track of when the layout has changed.
-    [[textView layoutManager] setDelegate:self];
-
-    // The text storage retains the layout manager which in turn retains the
-    // text container.
-    [tc release];
-    [lm release];
-
-    [self addNewTabViewItem];
-#else
     // Setup a complete text system.
     NSLayoutManager *lm = [[NSLayoutManager alloc] init];
     NSTextContainer *tc = [[NSTextContainer alloc] initWithContainerSize:
@@ -269,8 +245,8 @@ NSMutableArray *buildMenuAddress(NSMenu *menu)
     [textStorage addLayoutManager:lm];
     [lm addTextContainer:tc];
 
-    textView = [[MMTextView alloc] initWithPort:sendPort frame:[tabView frame]
-                                textContainer:tc];
+    textView = [[MMTextView alloc] initWithFrame:[tabView frame]
+                                   textContainer:tc];
 
     [[self window] makeFirstResponder:textView];
 
@@ -283,7 +259,6 @@ NSMutableArray *buildMenuAddress(NSMenu *menu)
     [lm release];
 
     [self addNewTabViewItem];
-#endif
 
     // NOTE! This flag is set once the entire text system is set up.
     setupDone = YES;
@@ -409,7 +384,7 @@ NSMutableArray *buildMenuAddress(NSMenu *menu)
 
 - (IBAction)addNewTab:(id)sender
 {
-    [NSPortMessage sendMessage:AddNewTabMsgID withSendPort:sendPort wait:NO];
+    [vimController sendMessage:AddNewTabMsgID data:nil wait:NO];
 }
 
 - (IBAction)showTabBar:(id)sender
@@ -446,8 +421,7 @@ NSMutableArray *buildMenuAddress(NSMenu *menu)
         // Propagate the selection message to the VimTask.
         int idx = [self representedIndexOfTabViewItem:tabViewItem];
         NSData *data = [NSData dataWithBytes:&idx length:sizeof(int)];
-        [NSPortMessage sendMessage:SelectTabMsgID withSendPort:sendPort
-                              data:data wait:YES];
+        [vimController sendMessage:SelectTabMsgID data:data wait:YES];
     }
 }
 
@@ -460,8 +434,7 @@ NSMutableArray *buildMenuAddress(NSMenu *menu)
     int idx = [self representedIndexOfTabViewItem:tabViewItem];
     //NSLog(@"Closing tab with index %d", idx);
     NSData *data = [NSData dataWithBytes:&idx length:sizeof(int)];
-    [NSPortMessage sendMessage:CloseTabMsgID withSendPort:sendPort
-                          data:data wait:YES];
+    [vimController sendMessage:CloseTabMsgID data:data wait:YES];
 
     return NO;
 }
@@ -472,8 +445,7 @@ NSMutableArray *buildMenuAddress(NSMenu *menu)
     NSMutableData *data = [NSMutableData data];
     [data appendBytes:&idx length:sizeof(int)];
 
-    [NSPortMessage sendMessage:DraggedTabMsgID withSendPort:sendPort
-                          data:data wait:YES];
+    [vimController sendMessage:DraggedTabMsgID data:data wait:YES];
 }
 
 
@@ -524,11 +496,24 @@ NSMutableArray *buildMenuAddress(NSMenu *menu)
 // -- NSWindow delegate ------------------------------------------------------
 
 
-#if 0
-- (void)windowWillClose:(NSNotification *)notification
+- (BOOL)windowShouldClose:(id)sender
 {
+    [vimController sendMessage:VimShouldCloseMsgID data:nil wait:YES];
+    return NO;
 }
 
+- (void)windowWillClose:(NSNotification *)notification
+{
+    //NSLog(@"%@ %s", [self className], _cmd);
+
+    // NOTE! There is a bug in PSMTabBarControl in that it retains the delegate
+    // (which is the MMWindowController) so reset the delegate here, otherwise
+    // the MMWindowController never gets released resulting in a pretty serious
+    // memory leak.
+    [tabBarControl setDelegate:nil];
+}
+
+#if 0
 - (NSSize)windowWillResize:(NSWindow *)sender toSize:(NSSize)proposedFrameSize
 {
     //NSLog(@"%s (%.2f,%.2f)", _cmd, proposedFrameSize.width,
@@ -725,8 +710,7 @@ NSMutableArray *buildMenuAddress(NSMenu *menu)
     NSMutableData *data = [NSMutableData data];
     [data appendBytes:&tag length:sizeof(int)];
 
-    [NSPortMessage sendMessage:ExecuteMenuMsgID withSendPort:sendPort
-                          data:data wait:NO];
+    [vimController sendMessage:ExecuteMenuMsgID data:data wait:NO];
 }
 
 - (MMScroller *)scrollbarForIdentifier:(long)ident index:(unsigned *)idx
@@ -871,8 +855,7 @@ NSMutableArray *buildMenuAddress(NSMenu *menu)
     [data appendBytes:&hitPart length:sizeof(int)];
     [data appendBytes:&value length:sizeof(float)];
 
-    [NSPortMessage sendMessage:ScrollbarEventMsgID withSendPort:sendPort
-                          data:data wait:YES];
+    [vimController sendMessage:ScrollbarEventMsgID data:data wait:YES];
 }
 
 - (void)fitWindowToScrollbars:(id)sender
@@ -902,10 +885,8 @@ NSMutableArray *buildMenuAddress(NSMenu *menu)
         //NSLog(@"Notify Vim that text storage dimensions changed to %dx%d",
         //        dim[0], dim[1]);
         NSData *data = [NSData dataWithBytes:dim length:2*sizeof(int)];
-        [NSPortMessage sendMessage:SetTextDimensionsMsgID
-                      withSendPort:sendPort
-                              data:data
-                              wait:![textView inLiveResize]];
+        [vimController sendMessage:SetTextDimensionsMsgID data:data
+                     wait:![textView inLiveResize]];
     }
 
     [tabView setFrame:textViewRect];
diff --git a/MacVim.h b/MacVim.h
index cd28046690..2945850216 100644
--- a/MacVim.h
+++ b/MacVim.h
@@ -11,6 +11,30 @@
 #import <Cocoa/Cocoa.h>
 
 
+#define MM_USE_DO 1
+
+
+
+#if MM_USE_DO
+
+@protocol MMBackendProtocol
+- (oneway void)processInput:(int)msgid data:(in NSData *)data;
+- (BOOL)checkForModifiedBuffers;
+@end
+
+@protocol MMFrontendProtocol
+- (oneway void)processCommandQueue:(in NSArray *)queue;
+@end
+
+@protocol MMAppProtocol
+- (byref id <MMFrontendProtocol>)connectBackend:
+    (byref in id <MMBackendProtocol>)backend;
+@end
+
+#endif
+
+
+
 enum {
     CheckinMsgID = 1,
     ConnectedMsgID,
@@ -44,9 +68,11 @@ enum {
     EnableMenuItemMsgID,
     ExecuteMenuMsgID,
     ShowToolbarMsgID,
+#if !MM_USE_DO
     TaskShouldTerminateMsgID,
     TerminateReplyYesMsgID,
     TerminateReplyNoMsgID,
+#endif
     CreateScrollbarMsgID,
     DestroyScrollbarMsgID,
     ShowScrollbarMsgID,
@@ -54,6 +80,7 @@ enum {
     SetScrollbarThumbMsgID,
     ScrollbarEventMsgID,
     SetFontMsgID,
+    VimShouldCloseMsgID,
 };