Mouse events pass through Mac Fullscreen Exit Bubble for Mouse Lock.

chrome/browser/ui/cocoa/fullscreen_exit_bubble_controller.mm

Index: chrome/browser/ui/cocoa/fullscreen_exit_bubble_controller.mm
diff --git a/chrome/browser/ui/cocoa/fullscreen_exit_bubble_controller.mm b/chrome/browser/ui/cocoa/fullscreen_exit_bubble_controller.mm
index c5908f88696bdfe87b121ef9525069e863390452..88ebc6dd8630b6c62a97e1ce5d353f04048270d2 100644
--- a/chrome/browser/ui/cocoa/fullscreen_exit_bubble_controller.mm
+++ b/chrome/browser/ui/cocoa/fullscreen_exit_bubble_controller.mm
@@ -76,6 +76,11 @@ const float kHideDuration = 0.7;
     owner_ = owner;
     url_ = url;
     bubbleType_ = bubbleType;
+    // Mouse lock expects mouse events to reach the main window immediately.
+    // Make the bubble transparent for mouse events if mouse lock is enabled.
+    if (bubbleType_ == FEB_TYPE_FULLSCREEN_MOUSELOCK_EXIT_INSTRUCTION ||
+        bubbleType_ == FEB_TYPE_MOUSELOCK_EXIT_INSTRUCTION)

[Nico, 2012/06/20 15:49:58]

These two types have no button on the bubble, right? If so, lgtm

[scheib, 2012/06/20 16:41:00]

Correct, these are exit instructions only for mouse lock (so nothing is
clickable).

+      [[self window] setIgnoresMouseEvents:YES];
   }
   return self;
 }