Windows generates fake raw mouse events for touchscreens for compatibility
with legacy apps that predate touch support in Windows. We already handle
touch events explicitly, so drop the synthetic events to avoid duplicates.
Closing the window is asynchronous, but we free the window data immediately,
so we can get an updateLayer callback before the window is really destroyed which
will cause us to access the freed memory.
Clearing the content view will cause it to be immediately released, so no further
updateLayer callbacks will occur.
Cameron Gutman