UserAgent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/50.0.2661.26 Safari/537.36

Steps to reproduce the problem:
1. Install application https://chrome.google.com/webstore/detail/chrome-hover-bug/cibhbaknlklbbackbancpdbeghnjhifd
2. Hover (move mouse) over the "Hover me!" area
3. Move mouse pointer outside of the app window
4. Doesn't get stuck on gray? Go to 2.
5. Gets stuck on gray state (:hover CSS) 

What is the expected behavior?
When you leave the app window the hover state should not be active any more. This should work reliable not to stay randomly stuck.

What went wrong?
The hover state on the "Hover me!" element got stuck. Even thou the mouse pointer is not over it anymore.

WebStore page: https://chrome.google.com/webstore/detail/chrome-hover-bug/cibhbaknlklbbackbancpdbeghnjhifd

Did this work before? No 

Chrome version: 50.0.2661.26  Channel: stable
OS Version: 7,8,10
Flash Version: Shockwave Flash 21.0 r0

This bug is on Linux and Window (7,8,10).
I was not able to reproduce this bug on Mac OS and Chrome OS.

It seems that this bug is somehow dependent on chrome.app.window "frame" (https://developer.chrome.com/apps/app_window#type-FrameOptions) when it's set to "none", because when the frame  property was omitted (default value "chrome"), the bug was not reproducible anymore.