Add deadzone to focus-follows-mouse

[dchang0]

Hello!

I like the focus-follows-mouse feature but not the max-scroll-amount sub-feature.
In addition to the max-scroll-amount, I'd like a deadzone specified by either pixels or percentage by which the user can move the mouse up to the deadzone amount into the neighboring window without triggering a change of focus and thus no scroll either.

The mouse can interact with the neighboring window while it is within the deadzone, so the deadzone is only for the focus-follows-mouse feature. For example, let's say the deadzone is 20px. and you move the mouse past the currently-focused window into the neighboring window to the left by 10px. You can use gestures to scroll the window to the left up and down but the window to the left still does not gain focus from the focus-follows-mouse feature. You can click on the window to the left while in the deadzone, which forces it to gain focus.

Basically, the deadzone allows a bit of overshoot past the edge of a window.

Thanks!