Window size and position options can be added to the "package.json" file in the Construct 2\exporters\html5\node-webkit folder.
(Make sure you back the original)
I added a max/min window size to a modded "package.json" file to stop the user resizing the game (works).
{
"main": "index.html",
"name": "[[[name]]]",
"description": "[[[description]]]",
"version": "[[[version]]]",
"window": {
"icon": "logo.png",
"toolbar": false,
"width": 960,
"height": 640,
"position": "center",
"min_width": 960,
"min_height": 640,
"max_width": 960,
"max_height": 640,
"show": false
},
"chromium-args": "--disable-extensions --disable-plugins --disable-internal-flash --disable-popup-blocking --enable-gamepad --enable-html5-camera --allow-file-access-from-files"
Not sure if it works with mimified...not tested it.
GITHUB
Hope this helps.