mac: Bookmark bar drag and drop bug.

chrome/browser/ui/cocoa/bookmarks/bookmark_bar_folder_hover_state.mm

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import "chrome/browser/ui/cocoa/bookmarks/bookmark_bar_folder_hover_state.h"
 #import "chrome/browser/ui/cocoa/bookmarks/bookmark_bar_controller.h"
 
 @interface BookmarkBarFolderHoverState(Private)
 - (void)setHoverState:(HoverState)state;
 - (void)closeBookmarkFolderOnHoverButton:(BookmarkButton*)button;
@@ skipping 15 matching lines @@
       // CASE A: hoverButton_ == button implies we've dragged over
       // the same folder so no need to open or close anything new.
     } else if (hoverButton_ &&
                hoverButton_ != button) {
       // CASE B: we have a hoverButton_ but it is different from the new button.
       // This implies we've dragged over a new folder, so we'll close the old
       // and open the new.
       // Note that we only schedule the open or close if we have no other tasks
       // currently pending.
 
+      // Since the new bookmark folder is not opened until the previous is
+      // closed, the NSDraggingDestination must provide continuous callbacks,
+      // even if the cursor isn't moving.
       if (hoverState_ == kHoverStateOpen) {
         // Close the old.
         [self scheduleCloseBookmarkFolderOnHoverButton];
       } else if (hoverState_ == kHoverStateClosed) {
         // Open the new.
         [self scheduleOpenBookmarkFolderOnHoverButton:button];
       }
     } else if (!hoverButton_) {
       // CASE C: we don't have a current hoverButton_ but we have dragged onto
       // a new folder so we open the new one.
@@ skipping 118 matching lines @@
 // Called after a delay to open a new hover folder.
 // Note: this method is not meant to be invoked directly, only through
 // a delayed call to |scheduleOpenBookmarkFolderOnHoverButton:|.
 - (void)openBookmarkFolderOnHoverButton:(BookmarkButton*)button {
   [self setHoverState:kHoverStateOpen];
   [[button target] performSelector:@selector(openBookmarkFolderFromButton:)
       withObject:button];
 }
 
 @end