Karabiner-Elements: shift-click broken

I just installed the latest Karabiner-Elements on my iMac running the Sierra GM. I love that the “fn” key once again works as left control, but shift-click no longer works to extend the selection. Reasonable trade-off, but slightly annoying.

Here’s my karabiner.json:

{
    "profiles": [
        {
            "name": "Default profile",
            "selected": true,
            "simple_modifications": {
                "fn": "left_control"
            }
        }
    ]
}