Avoid window flashing white when opened (final)

The previous commit would not present the window until all plugins etc.
had been loaded.  Since this can take a significant time it may seem
like no window is opening.  This commit opens a blank window as soon as
possible.

(Also fixes a regression introduced by the last commit where opening
multiple files in tabs from Terminal would cause two tablines to be
displayed.)

src/MacVim/MMAppController.m

@@ -1914,6 +1914,11 @@ fsEventCallback(ConstFSEventStreamRef streamRef,
     [cachedVimControllers removeObjectAtIndex:0];
     [vc setIsPreloading:NO];
 
+    // If the Vim process has finished loading then the window will displayed
+    // now, otherwise it will be displayed when the OpenWindowMsgID message is
+    // received.
+    [[vc windowController] presentWindow:nil];
+
     // Since we've taken one controller from the cache we take the opportunity
     // to preload another.
     [self scheduleVimControllerPreloadAfterDelay:1];

src/MacVim/MMBackend.m

@@ -473,6 +473,9 @@ extern GuiFont gui_mch_retain_font(GuiFont font);
 
     [self queueMessage:OpenWindowMsgID data:nil];
 
+    // HACK: Clear window immediately upon opening to avoid it flashing white.
+    [self clearAll];
+
     return YES;
 }
 

src/MacVim/MMVimController.h

@@ -41,7 +41,6 @@
 #endif
     BOOL                isPreloading;
     NSDate              *creationDate;
-    BOOL                windowHasBeenPresented;
 }
 
 - (id)initWithBackend:(id)backend pid:(int)processIdentifier;

src/MacVim/MMVimController.m

@@ -548,14 +548,17 @@ static BOOL isUnsafeMessage(int msgid);
 {
     if (OpenWindowMsgID == msgid) {
         [windowController openWindow];
+
+        // HACK: Delay actually presenting the window onscreen until after
+        // processing the queue since it contains drawing commands that need to
+        // be issued before presentation; otherwise the window may flash white
+        // just as it opens.
+        if (!isPreloading)
+            [windowController performSelector:@selector(presentWindow:)
+                                   withObject:nil
+                                   afterDelay:0];
     } else if (BatchDrawMsgID == msgid) {
         [[[windowController vimView] textView] performBatchDrawWithData:data];
-
-        // HACK! In order to avoid the window flashing white on startup we take
-        // care to only present the window on screen once something has been
-        // drawn to it.
-        if (!windowHasBeenPresented)
-            windowHasBeenPresented = [windowController presentWindow];
     } else if (SelectTabMsgID == msgid) {
 #if 0   // NOTE: Tab selection is done inside updateTabsWithData:.
         const void *bytes = [data bytes];

src/MacVim/MMWindowController.h

@@ -48,7 +48,7 @@
 - (void)setWindowAutosaveKey:(NSString *)key;
 - (void)cleanup;
 - (void)openWindow;
-- (BOOL)presentWindow;
+- (BOOL)presentWindow:(id)unused;
 - (void)updateTabsWithData:(NSData *)data;
 - (void)selectTabWithIndex:(int)idx;
 - (void)setTextDimensionsWithRows:(int)rows columns:(int)cols isLive:(BOOL)live

src/MacVim/MMWindowController.m

@@ -263,7 +263,7 @@
                           keepOnScreen:YES];
 }
 
-- (BOOL)presentWindow
+- (BOOL)presentWindow:(id)unused
 {
     // Actually show the window on screen.  However, if openWindow hasn't
     // already been called nothing will happen (the window will be displayed