This test was disabled in bug 556853. We should find out why there is a difference between 10.5 and 10.6.

The event that is lost is the first mouse move event after a tooltip opens, and we send it to the tooltip. We want the tooltip window to redirect the event to any of our ChildViews which will redirect it to the right ChildView using the ChildViewMouseTracker. The problem here is that the event never reaches any of our child views. -[PopupWindow sendEvent:] wants to send it to the tooltip window's first responder, but at this point the tooltip window doesn't have a firstResponder NSView. Instead, the firstResponder is the tooltip NSWindow itself, and sending the event to the NSWindow means we lose it. (It also means we have a bad cast!) Instead we should send the event to the content view, which is a ChildView that we control. I'm not sure why that only happens on 10.6. I'll tweak test_native_mouse_mac.xul in bug 392188 to account for this. I've also seen this bug with tooltips on background windows (after bug 392188) - sometimes we just stopped responding to mouse moves, which resulted in sticky tooltips.