UserAgent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/60.0.3112.90 Safari/537.36

Steps to reproduce the problem:
(Will show an example with YouTube video uploader)
1. Go to the page to upload a YouTube video
2. Click on the option to chose a video to upload
3. Drag and drop any file from the explorer to the browser
4. You will notice that when pressing the tab option that you can see the focus moving around when you still have the file explorer on

What is the expected behavior?
Even after drag and drop the focus should be on the file explorer since you can navigate through the site using the tab key on your keyboard and do more stuff that you shouldn't be allowed

What went wrong?
The focus of the browser is not set on the explorer anymore, it is set on the back of the file explorer which shouldn't be able to be done (because the priority was set on the file explorer)

Did this work before? N/A 

Chrome version: 60.0.3112.90  Channel: stable
OS Version: 10.0
Flash Version: 

Reported in another bug which is a crash because it helped the crash to reproduce easily (https://bugs.chromium.org/p/chromium/issues/detail?id=751133)

Also wanted to report as a security issue, because it bypass the explorer and who knows if any website could have a problem with that

This bug can be done on any site as long as it has an option that will open the file explorer (if you drag and drop a zip it will keep the page intact but the focus will be in the back)

Also wanted to choose "security" as the type of bug since it bypass the fact you shouldn't be able to control what is behind the file explorer, but wasn't sure.
 

Deleted: loosing focus bug.gif 2.0 MB

	loosing focus bug.gif 2.0 MB View Download