Start a drag if the tab is dragged off the sides of the window....

chrome/browser/cocoa/tab_strip_controller.mm

 // Copyright (c) 2009 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/cocoa/tab_strip_controller.h"
 
 #include "app/l10n_util.h"
 #include "base/mac_util.h"
 #include "base/sys_string_conversions.h"
 #include "chrome/app/chrome_dll_resource.h"
@@ skipping 19 matching lines @@
 #include "chrome/browser/tabs/tab_strip_model.h"
 #include "grit/generated_resources.h"
 #include "skia/ext/skia_utils_mac.h"
 
 NSString* const kTabStripNumberOfTabsChanged = @"kTabStripNumberOfTabsChanged";
 
 // A value to indicate tab layout should use the full available width of the
 // view.
 static const float kUseFullAvailableWidth = -1.0;
 
+// Left-side indent for tab layout so tabs don't overlap with the window
+// controls.
+static const float kIndentLeavingSpaceForControls = 64.0;
+
 // A simple view class that prevents the Window Server from dragging the area
 // behind tabs. Sometimes core animation confuses it. Unfortunately, it can also
 // falsely pick up clicks during rapid tab closure, so we have to account for
 // that.
 @interface TabStripControllerDragBlockingView : NSView {
   TabStripController* controller_;  // weak; owns us
 }
 
 - (id)initWithFrame:(NSRect)frameRect
          controller:(TabStripController*)controller;
@@ skipping 264 matching lines @@
 
 - (void)insertPlaceholderForTab:(TabView*)tab
                           frame:(NSRect)frame
                   yStretchiness:(CGFloat)yStretchiness {
   placeholderTab_ = tab;
   placeholderFrame_ = frame;
   placeholderStretchiness_ = yStretchiness;
   [self layoutTabs];
 }
 
+- (BOOL)isTabFullyVisible:(TabView*)tab {
+  NSRect frame = [tab frame];
+  return NSMinX(frame) >= kIndentLeavingSpaceForControls &&
+      NSMaxX(frame) <= NSMaxX([tabView_ frame]);
+}
+
 - (void)showNewTabButton:(BOOL)show {
   forceNewTabButtonHidden_ = show ? NO : YES;
   if (forceNewTabButtonHidden_)
     [newTabButton_ setHidden:YES];
 }
 
 // Lay out all tabs in the order of their TabContentsControllers, which matches
 // the ordering in the TabStripModel. This call isn't that expensive, though
 // it is O(n) in the number of tabs. Tabs will animate to their new position
 // if the window is visible and |animate| is YES.
 // TODO(pinkerton): Handle drag placeholders via proxy objects, perhaps a
 // subclass of TabContentsController with everything stubbed out or by
 // abstracting a base class interface.
 // TODO(pinkerton): Note this doesn't do too well when the number of min-sized
 // tabs would cause an overflow.
 - (void)layoutTabsWithAnimation:(BOOL)animate
              regenerateSubviews:(BOOL)doUpdate {
-  const float kIndentLeavingSpaceForControls = 64.0;
   const float kTabOverlap = 20.0;
   const float kNewTabButtonOffset = 8.0;
   const float kMaxTabWidth = [TabController maxTabWidth];
   const float kMinTabWidth = [TabController minTabWidth];
   const float kMinSelectedTabWidth = [TabController minSelectedTabWidth];
 
   NSRect enclosingRect = NSZeroRect;
   [NSAnimationContext beginGrouping];
   [[NSAnimationContext currentContext] setDuration:0.2];
 
@@ skipping 603 matching lines @@
   BrowserWindowController* controller =
       (BrowserWindowController*)[[switchView_ window] windowController];
   DCHECK(index >= 0);
   if (index >= 0) {
     [controller setTab:[self viewAtIndex:index] isDraggable:YES];
   }
 }
 
 
 @end