Mac: Prevent mouse events reaching subviews while a window has an attached Sheet

chrome/browser/ui/cocoa/tabs/tab_strip_view.mm

 // Copyright (c) 2012 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/tabs/tab_strip_view.h"
 
 #include <cmath>  // floor
 
 #include "base/logging.h"
 #include "base/mac/foundation_util.h"
@@ skipping 209 matching lines @@
   return YES;
 }
 
 // We accept first mouse so clicks onto close/zoom/miniaturize buttons and
 // title bar double-clicks are properly detected even when the window is in the
 // background.
 - (BOOL)acceptsFirstMouse:(NSEvent*)event {
   return YES;
 }
 
+// When displaying a modal sheet, interaction with the tabs (e.g. middle-click
+// to close a tab) should be blocked. -[NSWindow sendEvent] blocks left-click,
+// but not others. To prevent clicks going to subviews, absorb them here. This
+// is also done in FastResizeView, but TabStripView is in the title bar, so is
+// not contained in a FastResizeView.
+- (NSView*)hitTest:(NSPoint)aPoint {
+  if ([[self window] attachedSheet])
+    return self;
+  return [super hitTest:aPoint];
+}
+
 // Trap double-clicks and make them miniaturize the browser window.
 - (void)mouseUp:(NSEvent*)event {
   // Bail early if double-clicks are disabled.
   if (![self doubleClickMinimizesWindow]) {
     [super mouseUp:event];
     return;
   }
 
   NSInteger clickCount = [event clickCount];
   NSTimeInterval timestamp = [event timestamp];
@@ skipping 178 matching lines @@
   } else {
     [visualEffectView setState:NSVisualEffectStateFollowsWindowActiveState];
   }
 }
 
 - (void)windowDidChangeActive {
   [self setNeedsDisplay:YES];
 }
 
 @end