What's the difference between touch event enable & automatic in Chrome

In chrome://flags page, there is a setting named Enable touch events. It's set to Automatic by default. I wonder what's the difference between Automatic & Enabled. I ask this because they behave different in some pages. For example, http://smartclient.com/smartgwt/showcase/#main.

Steps to see the difference:

1. Open Chrome, navigate to the web page
2. Open dev tool, toggle to emulator mode by click icon on the top left of console window
3. Refresh page to make sure page ruing in emulator mode
4. Try to click elements on the web page

Result:

• When setting to Automatic, elements don't respond to click
• When setting to Enabled, elements respond to click

BTW, I'm using Chrome v51.

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