Is there a way to control atom dock layout

I created a browser in left dock like the picture below,

and I was having a trouble to set the width of left dock, because i want to show the html page fullscreen at Atom has started.

I have found some api in atom’s documentation and also looked up some function in atom’s source,
only got more puzzled

Docks aren’t designed to be fullscreened.

since I can drag the edge of the left dock‘s’ border,I thought there may be a way to control the width by source

Just like you can with any HTML element, yes. The docks, however, aren’t designed for that and trying to make them do it might cause undesired behavior with the rest of Atom. There’s nothing in the API to do it because that’s not how they were designed, so the only way I know of is to use brute-force DOM manipulation.

Thanks a lot!
I just changed the code in dock.js,these two variables define the initial size of dock

const MINIMUM_SIZE = 100

const DEFAULT_INITIAL_SIZE = 300

Update:
I added a function in dock.js to modify the width of left dock perfectly

modifyBorder (width) {
this.setState({size: width})
}

HI, could you tell me where can I find the dock.js??Thanks.